BERLIN — The North Atlantic Treaty Organization, known as NATO, grew largely out of Cold War fears of Soviet aggression and expansionism following a communist coup in Czechoslovakia, the Soviet blockade of Berlin and other incidents. It also was meant to prevent the resurgence of nationalist militarism and to encourage political integration in Europe.
The United States, Canada, Belgium, Denmark, France, Iceland, Italy, Luxemburg, the Netherlands, Norway, Portugal, and the United Kingdom signed the initial treaty on April 4, 1949. Since then, the trans-Atlantic security arrangement has more than doubled in membership and changed its mandate significantly. Here are some highlights:
WHAT DOES NATO DO?
NATO initially was largely a political alliance. That changed quickly after the Soviets detonated an atomic bomb in 1949 and the Korean War broke out in 1950. The events prompted members to establish a centralized headquarters, to commit joint military resources and to commit to "safeguard the freedom, common heritage and civilization of their peoples, founded on the principles of democracy, individual liberty and the rule of law."
A key provision of the treaty, the so-called Article 5, states that if one member of the alliance is attacked in Europe or North America, it is to be considered an attack on all of them. That effectively put Western Europe under the "nuclear umbrella" of the United States.
The head of the alliance is always a civilian secretary general, currently former Norwegian Prime Minister Jens Stoltenberg . NATO is led militarily by the Supreme Allied Commander Europe, who is also the commanding general of the Stuttgart-based U.S. European Command, currently Gen. Curtis Scaparrotti .
The only time NATO's Article 5 mutual defense provision has been invoked was in support of the United States after the Sept. 11, 2001, attacks on New York and Washington. In response, the alliance activated AWACS reconnaissance flights over the U.S. for months, operations that included 830 crew members from 13 NATO countries. It also launched maritime operations in the Mediterranean, and participated in U.S.-led efforts in Afghanistan, where it has led the mission since 2003.
WHO BELONGS TO NATO?
NATO has grown from the original 12 nations to an alliance of 29. Several other nations are in membership negotiations.
The first expansion, in 1952, admitted Greece, Turkey and West Germany into the alliance. In response to NATO's growth and decision on West Germany, the Soviet Union and its Eastern European client states in 1955 formed the eight-nation Warsaw Pact. East Germany was included in the pact, which had a mutual defense agreement of its own.
The Warsaw Pact dissolved in 1991 following the fall of the Berlin Wall and the reunification of Germany, but NATO continued to expand. It now counts all seven non-Soviet former Warsaw Pact nations as alliance members.
Though pledged to defend one another, NATO nations have not always seen eye-to-eye. Never was this more apparent than in 1966, when founding member France announced it was leaving NATO's integrated military command structure to pursue its own defense strategy and asked the alliance to remove all Allied headquarters from its soil.
The alliance relocated from its initial base outside Paris to Belgium, where it remains today. Despite the move, France did not leave NATO, emphasizing its commitment to the mutual defense pact. But France continued developing its own nuclear deterrent.
The French leader at the time, President Charles de Gaulle, said the intention was to "modify the form of our Alliance, without altering its substance." France rejoined NATO's military structure in 2009.
Much has been made of the alliance's goal for member nations to spend at least 2 percent of gross domestic product on defense. U.S. President Donald Trump routinely contends that most members are shirking their commitments by failing to get there.
The reality is that in 2014, NATO members agreed to stop cutting their military budgets and set a goal of moving "toward" spending 2 percent of their gross domestic products on defense by 2024. NATO defines defense expenditure as payments by a government to meet the needs of its own armed forces, those of its allies or the alliance — not a payment of funds to NATO itself.
According to this month's figures from NATO, the U.S. commitment is the highest with 3.5 percent of GDP, followed by Greece with 2.27 percent, Estonia with 2.14 percent and the United Kingdom with 2.1 percent. Latvia also meets the 2 percent goal, and Poland, Lithuania and Romania are expected to by year's end. None of the alliance's other members meet the target.
NATO and the Warsaw Pact did not clash head-to-head during the Cold War, but the alliance has been busy in military engagements since the collapse of the Soviet Union. It says some 20,000 military personnel are currently engaged in NATO missions around the world, operating in Afghanistan, Kosovo and the Mediterranean.
NATO conducted its first military intervention in Bosnia, implementing aspects of the Dayton Peace Agreement that marked the end of the 1992-1995 war. Its Implementation Force, or IFOR, was deployed in Bosnia in December 1995, followed by a Stabilization Force, or SFOR, which ended in December 2004.
The alliance also took over leadership of the ISAF mission in Afghanistan in 2003 and currently leads the follow-on Resolute Support mission. It also supports the African Union in peacekeeping missions, has sent trainers to Iraq, assisted in counter-piracy missions in the Gulf of Aden and off the Horn of Africa, and enforced a no-fly zone over Libya, where it now has sole command and control of all military operations.
The alliance also has been involved in protecting public events like the Olympic Games in Greece in 2004, assisted in the aftermath of Hurricane Katrina in the United States in 2005, and provided aid in Pakistan after a devastating 2005 earthquake.