CRS Report for Congress
NATO: A Brief History of Expansion
Susanne Stetzer*
Research Assistant
Foreign Affairs and National Defense Division
NATO has admitted new members on three different occasions. Depending on the
countries admitted, debates in Congress have concentrated upon strategic and political
issues, including burdensharing. From NATO’s origins, Congress has shown strong
interest in sharing the strategic and economic responsibilities in providing for Europe’s
defense. NATO admitted Greece and Turkey to the alliance in 1952, the Federal
Republic of Germany in 1955, and Spain in 1982.
This chronology traces the origins of the North Atlantic Treaty Organization and its
subsequent expansions. It is not an exhaustive list of the key events of NATO’s history.
It concerns events relevant to the enlargement process.1

06/05/47 — The Marshall Plan for economic rehabilitation of Europe was announced.

03/17/48 —France, Britain, Belgium, the Netherlands, and Luxembourg signed the
Brussels Treaty, pledging collective defense for member states, for a
duration of 50 years. President Truman praised the treaty as an important
step for building European stability.
06/11/48— The U.S. Senate passed the Vandenberg Resolution endorsing collective
defense organizations. Prospective US involvement would only be to
“supplement, rather than replace, the efforts of the other participants on2
their behalf.”

*Prepared under the supervision of Paul Gallis, Specialist in European Affairs.
1For an examination of NATO enlargements through 1982, see CRS Report 97-1041, Senate
Consideration of the North Atlantic Treaty and Subsequent Accessions: Historical Overview, by
Stanley R. Sloan.
2See North Atlantic Treaty, Senate Foreign Relations Committee Report. 81st Congress, 1st sess.
Washington, June 6, 1949.
Congressional Research Service ˜ The Library of Congress

07/24/48—The Soviets blocked ground access to Berlin. The United States launched
a massive airlift to supply the city.

12/10/48—Negotiations on the North Atlantic Treaty opened in Washington.

04/04/49—The United States, France, Britain, Italy, the Netherlands, Belgium,

Canada, Denmark, Iceland, Luxembourg, Norway, and Portugal signed
the North Atlantic Treaty in Washington.

04/08/49—The Brussels Treaty Powers, together with Denmark, Italy, and Norway,

appealed for U.S. military and financial assistance.
04/27/49—As part of the debate over the North Atlantic Treaty, a Senate hearing
addressed burdensharing, collective defense, and congressional authority
over war powers. Secretary of State Dean Acheson said “that no party
can rely on others for its defense unless it does its utmost to defend itself
and contribute toward the defense of the others.” He had previously stated
that military and financial aid would be given to the Brussels Treaty
powers if they made substantial efforts for their own defense. He appealed
for support for NATO as a key to protecting US interests.3

07/21/49—The U.S. Senate ratified the North Atlantic Treaty by a vote of 82-13,

following 13 days of debate.
06/25/50—North Korean forces attacked South Korea. The conflict heightened
concern over the spread of communism and led the Truman
Administration to station more troops in Europe.
12/20/50—The Brussels Treaty powers merged the military command structure of the
Western Union with NATO.
02/07/52—The US Senate approved the protocol inviting Greece and Turkey to join
NATO, 73-2. Both had established close military and political ties with
the United States following World War II. Turkey’s strategic geographic
location was a decisive factor in its admittance, particularly in light of the
Soviet desire to expand its control and influence in the region. Former
agreements between Greece and Britain and France strengthened US
support for Greece’s admittance to NATO.

02/18/52—Greece and Turkey acceded to the North Atlantic Treaty.

08/29/54—The French National Assembly failed to ratify a treaty to establish the
European Defense Community (EDC), which would have created a
European army, including a few German units, under a European decision-
making structure. This had been the French government’s solution for the
question of German rearmament and integration into European defense.

3For a discussion of the evolution of the idea of collective defense in the United States, see CRS
Report 97-717, NATO: Article V and Collective Defense, by Paul E. Gallis.

10/23/54—After the failure of the EDC, the Western European Union, formerly the
Western Union, was formed, following the accession of Italy and the
Federal Republic of Germany (FRG) to the Brussels Treaty.
04/01/55—The U.S. Senate approved a protocol to admit Germany to NATO by a
vote of 76-2, and the FRG became a member on May 9. A few Senators
were wary of Germany, but a large majority believed that a democratic
government was well-established. Sen. George (D- Georgia) stated that
Germany was already an integral part of the North Atlantic Community
economically and geographically. Strategically, he said, “The difficulty
— one might almost say impossibility — of defending western Europe
without Germany has long been obvious.” Militarily and geographically,
Germany was viewed as an asset to NATO. At accession, Germany’s
armed forces were minimal.
05/16/55—In response to the FRG’s incorporation into NATO, the German
Democratic Republic (East Germany) joined the Soviet Union and other
eastern European countries in the Warsaw Pact.
01/01/58—The Treaty of Rome established the European Economic Community
(EEC), intended to build political and economic stability in western
Europe. The United States strongly backed its creation.
08/09/61—The Berlin Crisis began. The Soviets threatened to give the East German
Government control over Berlin and limit Allied access to the city. The
Berlin Wall was built, and President Kennedy mobilized conventional
forces to defend Allied rights in the city.
03/10/66—President de Gaulle formally announced France’s intention to withdraw
from the integrated command structure of the alliance.

08/31/66—The so-called Mansfield Resolution was first introduced in the U.S.

Senate. Sen. Mansfield (D-Montana) called for a substantial reduction in
US forces in Europe and expressed a desire to see Europeans share a
greater part of the conventional defense burden, but did not call into
question the US commitment to NATO. Sen. Mansfield cited
commitment of US resources in Vietnam, French withdrawal from the
integrated command structure, and domestic financial troubles as the
reasons for his resolutions.
04/21/67—A coup led to a military junta in Greece. Over time, the allies placed
restrictions on the Greek government’s participation in NATO councils.
12/13-14/67—The North Atlantic Council (NAC) approved the Harmel Report, which
stated that NATO must maintain sufficient military strength for the
collective defense of its territory and to deter aggression, but at the same
time promote detente.
05/30/72 —Multilateral negotiations on mutual and balanced conventional force
reductions (MBFR) were proposed by NATO.

07/03/73 —The Conference on Security and Cooperation in Europe (CSCE) opened
in Helsinki, and was intended to promote improved political and economic
relations and an easing of tensions between East and West in Europe.

04/25/74 — A military coup in Portugal ushered in a democratic government.

07/24/74 —A democratic government assumed power in Greece, and NATO
restrictions were lifted.
04/31/75 —The heads of state and government of the 35 participating states signed the
CSCE Helsinki Final Act.
05/18/77 —President Carter proposed that the NATO countries in the integrated
command structure increase their defense spending by 3% per year,
depending on the status of each country’s economy and military.
12/12/79 —The alliance approved the goal of basing of U.S. intermediate nuclear
forces (INF) in Europe. The weapons were meant to strengthen the US
nuclear guarantee and spur arms control of such weapons with the USSR.
Fearing detente could be damaged, some allies hesitated to base the
weapons. The first deployment of missiles occurred on Nov. 14, 1983, at
Greenham Common air base in Britain.
09/12/80 —After a period of widespread disorder, a military government assumed
power in Turkey.
03/16/82 —After minimal debate, a voice vote in the U.S. Senate approved a protocol
to admit Spain to the alliance, and it joined on 30 May. General Franco’s
death in 1976 had ended dictatorship in Spain and opened the way for
democracy and a viable candidacy to join NATO. Some U.S. Senators
had argued in favor of Spain joining in 1952 with Turkey and Greece, and
for decades there had been U.S. military installations there. In 1976, the
United States and Spain had signed a military and economic cooperation

12/13/83 —Under a new constitution, a civilian government was formed in Turkey.

01/01/86 —Portugal and Spain joined the EEC.

03/12/86 —Spanish voters expressed support for Spain’s membership in the alliance,

but without participation in integrated command structure.
12/08/87 —The Senate gave its advice and consent to the Treaty on US-Soviet
Intermediate-Range Nuclear Forces (INF), eliminating all INF systems.
11/10/89 —The Berlin Wall fell, following the resignation of the East German

1989-1991—Communist regimes in eastern Europe collapsed.

07/06/90 —NATO heads of state and government published the ‘London
Declaration’, a proposal to develop cooperation between NATO countries
and those of Central and Eastern Europe in political and military matters
in light of the changing face of Europe.
10/03/90 —The newly reunified Germany was recognized by the NAC as a member
of NATO.
11/19/90 —The Conventional Armed Forces in Europe (CFE) Treaty to reduce
conventional forces on the continent was signed by NATO and the
Warsaw Pact.

04/01/91 —The Warsaw Pact was dissolved.

11/08/91 —NATO announced the new Strategic Concept, a guideline for
reconfiguration of member states’ forces for new missions such as crisis
management and peacekeeping. It described the Soviet Union as a
‘former adversary,’ and encouraged its first steps to democracy.
12/20/91 —North Atlantic Cooperation Council (NACC) conducted the first meeting
between representatives from each of the sixteen NATO countries and
nine Central and East European countries.
11/06/92 —NATO provided equipment, supplies, a staff of approximately 100, and
a headquarters to UN forces in Bosnia.

04/12/93 —NATO AWACS and Allied aircraft were employed to enforce the UN ‘no-

fly’ zone over Bosnia-Herzegovina.
01/10/94 —In Brussels, NATO heads of state and government launched Partnership
for Peace (PfP). NACC and CSCE countries were invited to join,
provided they were willing and able to participate. Measures were taken
to support development of a European Security and Defense Identity.
NATO expansion was proposed.
01/01/95 —CSCE became the Organization for Cooperation and Security in Europe
09/20/95—The NAC issued a report on the expansion of the alliance to Central and
East European countries under the guidelines that candidates develop
democratic structures, a free market economy, and civilian control of the
12/15/95 —The United Nations approved NATO’s Implementation Force (IFOR) for
Bosnia, the alliance’s first land operation outside the NATO area, to
implement the Dayton Peace Accords, signed the previous day.

11/16/96—The Spanish Parliament supported the government’s decision in principle
to begin the process of Spain’s integration into NATO’s military
command structure.
05/27/97 —NATO and Russia signed the “Founding Act” in Paris for cooperation in
security matters.
07/8-9/97 —NATO heads of government met in Madrid and invited the Czech
Republic, Hungary, and Poland to begin negotiations for accession.
Members emphasized the candidate states’ ability to contribute to new
missions as a key contributing factor in their nomination. If approved by
all 16 governments or parliaments of existing members, the three
countries may join the Alliance on April 4, 1999. NATO enlargement and
internal reform were declared continuing processes. (France stated NATO
reform had not sufficiently progressed to warrant its full participation in4
the integrated command structure.)
11/10/97 —Poland, the Czech Republic, and Hungary completed their accession
negotiations with the alliance.
12/16-17/97—A NATO ministerial drafted a protocol, to be submitted to member states
and parliaments, to admit the three candidate states. Reform of the5
alliance’s command structure was approved.
04/30/98 — The Resolution of Ratification was passed by the Senate, 80-19, giving its
consent to NATO enlargement. The resolution endorsed the core purpose
of NATO as being collective defense. In debate, the Senate stressed
enlargement’s cost, potential threats, how Russia might be affected, and
NATO’s openness to future expansion.

4See CRS Issue Brief 95076, NATO: Congress addresses Expansion of the Alliance, by Paul E.
Gallis; CRS Report 97-443, NATO: The July 1997 Madrid Summit Outcome, by Stanley R. Sloan;
and CRS Report 97-666, NATO Enlargement: the Process and Allied Views, by Paul E. Gallis.
5See CRS Report 98-9, NATO Internal Adaptation: The New Command Structure and the Future
of the European Pillar, by Louis R. Golino.