National Security Implications of Airborne Early Warning (AEW) Aircraft
CRS Report for Congress
Received through the CRS Web
National Security Implications of Airborne
Early Warning (AEW) Aircraft
Richard F. Grimmett
Foreign Affairs, Defense, and Trade Division
Airborne early warning (AEW) aircraft significantly improve the effectiveness of
modern defensive and offensive air operations. Presently only a few countries
manufacture such aircraft. The demand for AEW aircraft, is growing however, as their
utility is recognized. AEW aircraft have been sought by China and India, each a party in
regional rivalries. Congress is likely to review the U.S. national security interests and
policies raised by these cases.
Introduction to Airborne Early Warning.
Airborne early warning (AEW) aircraft significantly improve the effectiveness of
modern defensive and offensive air operations. AEW aircraft provide a larger and clearer
view of the battlespace, and the ability to more coherently organize and employ large
numbers of aircraft over great distances and against a large number of threats or targets.
Because radar is effective only to the extent of its direct line of sight, the Earth’s
curvature limits the ability of most surface-based radars to detect low flying aircraft
beyond about 30 miles. Modern aircraft can travel this distance very quickly; potentially
eluding detection until they are literally on top of their target. By elevating early warning
radars, say to 30,000 feet, low flying enemy aircraft can be detected at ranges up to 250
miles, providing better ability to prepare defenses and eliminate devastating surprise
attacks. (Figure 1 illustrates this concept.)
AEW systems are often combined with command, control and communications (C3)
equipment – such as identification friend or foe (IFF), electronic and communications
intelligence (ELINT and COMINT), advanced navigation and jam-resistant tactical data
links. The resulting AWACS aircraft (Airborne Warning and Control System) can be used
not just to provide warning to defenses, but also to effectively control large numbers of
aircraft on both defensive and offensive missions, over a large area against a large
Congressional Research Service ˜ The Library of Congress
Figure 1: Comparison of Ground-based and Airborne Early Warning
Radar Coverage against Low Flying Aircraft
number of threats or targets. In sum, AWACS aircraft may be considered “force
multipliers.” They facilitate the coherent use of large numbers of aircraft, over great
distances against numerous threats or targets, that would otherwise operate in small
groups with relatively limited operational “vision.”
Summary of Select AEW Systems.1
AEW aircraft are very sophisticated, and even technologically advanced countries
like Britain have decided that purchasing such aircraft is more attractive than building
them. Thus, in 2000 only a few countries produce AEW aircraft.
The United States makes the E-3 Sentry and E-2 Hawkeye aircraft. Both aircraft are
distinguished by a large, slowly rotating disc-shaped surveillance radar attached to the
aircraft’s fuselage. These pulse-doppler radars can perform numerous surveillance
functions simultaneously, and track hundreds of objects at hundreds of miles. These
aircraft also employ a variety of C3 technologies in severe electronic warfare environments.
Designed to operate from aircraft carriers, the E-2 aircraft is noticeably smaller than the
Boeing 707 aircraft on which the E-3 is based.
The Russian A-50 Mainstay aircraft also employs a rotating pulse-doppler radar on
a large aircraft (IL-76) and most closely resembles the E-3. The Mainstay uses IFF,
electronic warfare (EW), and other C3 equipment. Some contend that the A-50 is not as
capable as the E-3,2 yet even the baseline A-50 can simultaneously track 50 fighter-sized
1 Only the most current and capable AEW aircraft are included here. This section does not address
legacy aircraft, such as the Russian-built Tu-126 Moss. This aircraft’s AEW capabilities are
rudimentary, and it has been phased out of most countries’ inventories. Nor does this section
include maritime reconnaissance aircraft – such as the British Nimrod aircraft or Search Water
radar – which have some modest early warning capabilities.
2 Federation of American Scientists. Beriev A-50 Mainstay [http://www.fas.org/nuke/guide/.htm]
targets at about 140 miles.3 Russia offers various A-50 variants for export to control air
defense and counter-air fighters such as the SU-27 and MiG-29.
Israel and Sweden have recently fielded AEW aircraft based on the most sophisticated
radar technology. Abandoning rotating pulse-doppler radars, the Israeli Phalcon and
Swedish Eyrie are electronically steered radar arrays that provide full 360 degree
surveillance coverage. The Erieye radar sits in a rectangular box mounted on the Argus
aircraft. The Phalcon radar has been tested on several aircraft, and conforms to the aircraft
fuselage. These radars put less stress and drag on the aircraft than do roto-domes. This,
in turn can result in longer time on station, longer lived aircraft, or the use of smaller, more
versatile aircraft. The Argus transmits its data to ground based controllers, while the
Phalcon’s 10-13 member on-board crew controls fighter operations directly.
AEW Aircraft in Military Operations.
The military value of AEW/AWACS aircraft has been proven in numerous conflicts.
The success of Israel, for instance, against Syrian aircraft in the 1982 Lebanon War owed
much to U.S.-built E-2 Hawkeye AEW aircraft in Israeli service. E-2s routinely detected
incoming Syrian aircraft at long range and vectored Israel fighters to surprise them.4 The
E-2s also supported Israeli air attacks. In 1985, Israeli F-15s, accompanied by an E-2 flew
1,500 miles to bomb PLO headquarters in Tunisia. By contrast, the British lack of AEW
aircraft is considered a major factor in the loss of two destroyers to cruise missiles
launched by Argentine fighters during the 1982 Falklands war. Lacking long range
surveillance, the British were forced to position the HMS Sheffield and HMS Coventry in
postures that increased their vulnerability.5
Carrier-based E-2C aircraft directed F-14 fighters during the strike against Libya in
1986. E-2Cs and AEGIS cruisers, working together, provided air superiority over the
fleet. Libyan aircraft probed U.S. defenses at least 153 times but never got into firing
position before being locked into the sights of a U.S. aircraft or AEGIS platform missile.6
During the 1991 Gulf War (Operation Desert Shield and Operation Desert Storm),
U.S. AEW aircraft contributed significantly to the coalition’s overwhelming air campaign.
E-3B aircraft provided 24-hour radar coverage throughout the war. AWACS gave early
warning of Iraqi air activity and helped control engagement of Iraqi aircraft. It also
supported strike packages. E-2C aircraft tailored tactical control, filtered intelligence, and
improved the situational awareness for Navy strike groups and Coalition forces.7
3 Jane’s Radar and Electronic Warfare 1997-1998. Jane’s Information Group. London.
4 Nordeen, Lon. Fighters Over Israel. Orion Books. New York, NY. 1990:163.
5 Luttwak, Edward, and Stuart L. Koehl. The Dictionary of Modern War. Harper Collins. New
York, NY. 1991: 10.
6 U.S. Navy Fact File. E-2C Hawkeye. June 18, 1999, and F.A.S. Web Page.
7 U.S. Department of Defense. Conduct of the Persian Gulf War: Final Report to Congress. April
NATO operated 33 E-3 aircraft in the 1999 conflict in Kosovo (Operation Allied
Force). AEW aircraft played a key role in a war that some analysts contend was won by
air power alone, and in which there was no allied fratricide and only two aircraft lost to
enemy defenses. AEW aircraft coordinated complicated maneuvers such as night time,
multinational aerial refuelings of up to 80 aircraft. A NATO E-3 also enabled the downing
of three MiG-29s only four minutes after they took off from an airfield in Serbia.8
China and AEW Acquisition
In recent years China has sought to upgrade significantly its conventional military
equipment. Its force modernization program has included purchases of advanced combat
helicopters, combat fighter aircraft, submarines and a variety of missiles. Russia has been
the principal source of most of these advanced military items. While China’s upgrade
efforts can be viewed as a logical effort to maintain and enhance the capability of its
military force structure, it also presents a worrisome situation for Taiwan. China continues
to regard Taiwan as a renegade province of the Chinese state and periodically has made
threatening gestures toward it. The United States, for its part, has undertaken, through
law and policy statements, a commitment to seek a peaceful resolution to the PRC-Taiwan
dispute. Pending such an outcome, the United States has provided military equipment to
Taiwan to enhance its ability to defend itself against military attack.9
China’s indigenous fighter aircraft are technologically inferior to Taiwan’s F-16s and
Mirage 2000 fighters. To address this weakness, China has imported Su-27 fighters from
Russia, which are of comparable quality to Western fighters. Yet currently, China only has
48 of these aircraft, compared to a Taiwanese force of 240 modern fighters controlled by
four E-2 Hawkeye AEW aircraft. The integration of AEW aircraft into China’s air force
would reduce many of these apparent deficiencies.
On July 12, 2000, a longstanding effort by China to acquire modern AEW capabilities
from Israel reached a climax when, in response to United States opposition, Israel10
suspended its proposal to sell its Phalcon AEW system to China. Under the suspended
contract the Chinese reportedly had the option to purchase between three and six aircraft
after receiving the first plane.11 Once it became clear that Israel would not be the source
of its AEW aircraft, the Chinese turned to their principal weapons suppler, Russia for a
possible alternative. During the late summer and fall of 2000, reports indicated that China
was considering seeking a number of Russian-built A-50E “Mainstay” AEW aircraft. This
8 Janssen, Joris. No Time Off for NATO’s AWACS in the Balkans. Jane’s Defense Weekly. May
9 For a detailed examination of China’s conventional weapons acquisitions see: CRS Report
RL30700, October 10, 2000.
10 In November 2001 it was reported that China and Israel had begun re negotiations on AEW
aircraft. Barbara Opall-Rome “China to Renegotiate Failed Israeli Spy Plane Deal.” Defense News.
November 5-11, 2001. p. 7.
11 For detailed background on the Israeli-Chinese AEW sale see: Israel’s Sale of Airborne Early
Warning Aircraft to China. CRS Report RS20583, July 13, 2000.
aircraft would be an upgraded version of the A-50 AEW system, and would include a
more advanced radar system than the standard Russian model of the A-50 aircraft.12
Published reports note an option for China is to lease two Russian A-50 aircraft for
an interim period so that China’s air force could conduct AEW training. During this
interim period, the Chinese would work with Russia to upgrade the radar and avionics to
be part of the newly built A-50E aircraft. Over a three year period, efforts would be
undertaken to reduce the A-50's current vulnerability to electronic countermeasures, and
to enhance its ability to engage in secure communication, among other things. The new A-
50E would be designed to track 300 airborne and sea targets at a range of 250 miles
compared to the A-50's current range of 140 miles. The A-50E would also be designed
to control up to 30 aircraft, such as the Su-27 and Su-30 fighter aircraft, while serving as
a C3 platform.13
On November 3-4, 2000, Russian Deputy Prime Minister Illya Klebanov discussed
the sale of A-50 AEW aircraft with the Chinese during a state visit to Beijing. It was
subsequently reported that an agreement to sell the aircraft to China was reached during
this visit. Press reports indicate that at least four new A-50E AEW aircraft would be sold.
On December 13, 2000, ITAR reported that initial delivery would begin in 2001.14
India and AEW Acquisition
India has long been a major arms client of the former Soviet Union and Russia. India
has also long regarded an AEW aircraft as a valuable asset for its military, having used the
Tu-126 Moss in its 1971 war with Pakistan. When Israel suspended its sale of the Phalcon
to China in July 2000, India reportedly discussed buying a system from Israel. Israel,
appears reluctant to make the sale, due to concerns over U.S. objections. India is also
concerned about U.S. objections. Russia wants to sell India an advanced version of its A-
50 AEW system. India has assessed the current A-50 aircraft this year, and has expressed
interest in obtaining it, if the plane can be upgraded. Indian software specialists are
working closely with Russian and Israeli companies to develop new software that will
improve the A-50's capabilities.15 Russia has reportedly offered to lease two A-50 aircraft
to India while a modernized A-50E is developed. Although Russian Prime Minister
Vladimir Putin signed a number of agreements for weapons sales to India during his state
visit to India in early October, no agreement was reached regarding a lease or sale of the
A-50 at that time. It appears that India is continuing to consider its options, either to
12 Defense News, July 31, 2000, p. 16; Defense Week, September 18, 2000, pp. 1, 14; Agence
France Presse, November 1, 2000; Reuters, November 3, 2000.
13 Defense News, July 31, 2000, p. 16; Defense Week, September 18, 2000, pp. 1, 14; Agence
France Presse, November 1, 2000; Reuters, November 3, 2000.
14 Hong Kong Agence France Presse, November 9, 2000; Moscow Nezavisimoye Voyennoye
Obozreniye (FBIS translation), November 10, 2000; Washington Post, November 19, 2000, p. 24.
and Aviation Week & Space Technology, December 4, 2000: p. 31.
15 Joshua Newton. “India Developing Advanced Software for Surveillance Aircraft.” Aerospace
Daily. August 23, 2001. p.5.
modify the A-50, or to explore a purchase of the Israeli Phalcon system if prospective U.S.
objections to its sale can be overcome.16
India already enjoys a quantitative and qualitative advantage over Pakistan’s air force.
It has 21 more fighter squadrons than Pakistan, and a larger number of modern aircraft.
Unlike Pakistan, India also has aerial refueling and electronic warfare aircraft. Improving
its AEW capabilities will increase India’s conventional aerial warfare capabilities. Perhaps
more troubling, however, are the potential implications for aerial delivery of nuclear
weapons. Many believe that India and Pakistan probably would rely on aircraft to
conduct any nuclear strike – at least until their nuclear weapons are reduced in size or their
missiles are made more powerful and reliable. Modern AEW aircraft could give India a
greater probability of neutralizing Pakistan’s air defense fighters.
Considerations for Congress
In light of these two case examples, the U.S. government is likely to consider the
adequacy of current regulations, policies, or multilateral agreements governing the transfer
of AEW aircraft. Given the potential effect that acquisition of advanced AEW aircraft
could have on China’s military capabilities, the U.S. government may consider what
courses of action are available to deter Russia from selling advanced AEW aircraft to
China. If the sale does go through, Congress may confront a request to augment Taiwan’s
defensive capabilities. U.S. naval and air forces in East Asia may also be faced with a
requirement to augment existing capabilities to counter potential threats posed by China’s
acquisition, and effective deployment of, AEW aircraft.
In view of the continuing tensions between India and Pakistan, the prospect of India
acquiring advanced AEW aircraft could tip the conventional and nuclear military balance
vis-a-vis Pakistan. This could lead to an escalation of conventional or nuclear military
acquisitions by Pakistan in response because any future significant armed conflict between
the two countries could prompt Pakistan to consider relying on nuclear weapons to avoid
a conventional military defeat. Congress may consider it appropriate to monitor
developments regarding the possible acquisition of AEW aircraft by India, and to support
efforts by the U.S. government and others to dissuade suppliers from selling such aircraft.
Some analysts argue that AEW aircraft confer more defensive capabilities than offensive17
capabilities, and are thus not dangerous weapons. Yet, others disagree with this analysis.
A 1987 book by an Indian Air Force officer, for instance, describes how the acquisition
of AEW by Pakistan would give the Pakistanis a significant advantage in aerial combat and
would prove destabilizing.18 The growing availability of these aircraft and their potent
affect on aerial combat capabilities could lead to the reevaluation of the prominence of the
AEW aircraft proliferation issue in U.S. national security policy formulation.
16 Defense News, August 14, 2000, p.1, ff; Defense Week, September 18, 2000, pp.1, 15; Flight
International, September 19, 2000, p.23; ITAR-TASS, September 21, 2000; United Press
International, October 4, 2000; Flight International, October 10, 2000, p. 24.
17 See CRS Archived Issue Brief IB81078 Arms Sales to Saudi Arabia: AWACS and the F-15
Enhancement, for a detailed discussion of this issue.
18 Singh, Jasjit, AWACS: The New Destabiliser. Lancer Press. New Delhi. 1987.