1945. Following World War II, the US Army begins planning for research and development of missile defenses. Meanwhile, US defense contractors conclude that such technology is beyond their current reach.

1957. US begins work on its first major missile defense effort, the Nike-Zeus system.

1962. After technology flaws doom the Nike-Zeus project, the US begins work on the Nike X missile defense program, which uses nuclear-tipped interceptors.

1966. US Defense Secretary McNamara announces that the Soviet Union has deployed its Galosh missile defense system.

September 1967. President Johnson announces plans to deploy the Sentinel missile defense system (a successor to the Nike X program).

February 1969. President Nixon delays deployment to review US nuclear programs.

March 1969. Now called Safeguard, the system is given go-ahead for deployment.

August 1969. US Senate votes to deploy Safeguard missile defense, with the Vice President casting a tie-breaking vote.

May 1972. US and Soviet Union sign the ABM Treaty, banning nationwide missile defenses and limiting each side to two missile defense sites with no more than 100 interceptors at each site.

July 1974. ABM Treaty amended to allow only one limited missile defense site to each side.

October 1, 1975.. Safeguard system begins operating in Grand Forks, ND.

October 2, 1975. US House of Representatives votes to close the Grand Forks Safeguard site.

January 1976. The full Congress approves shutting down Safeguard, and Secretary of Defense Donald Rumsfeld announces the system’s termination.

1978. The Safeguard system is terminated completely.

March 23, 1983. President Reagan announces that the US will start an expanded research and development program of missile defense system which makes "nuclear weapons impotent and obsolete." His idea becomes the "Strategic Defense Initiative," or SDI. Opponents call it "Star Wars."

April 24, 1984. Secretary of Defense Weinberger signs a Strategic Defense Initiative Organization (SDIO) charter.

October 1986. President Reagan and Soviet President Gorbachev discuss the complete elimination of nuclear weapons, but the proposal collapses when Reagan refuses to agree to limitations on SDI.

June 14, 1989. President Bush decides to continue the SDI program, but focus on the development of "Brilliant Pebbles," a space-based interceptor design.

July 31, 1989. Presidents Bush and Gobachev sign START I, reducing arsenals to 6,000 deployed warheads on each side.

January 29, 1991. President Bush announces the Global Protection Against Limited Strikes (GPALS) system to counter unauthorized, accidental or limited attacks.

February 1991. During the Persian Gulf War, the US Patriot missile attempts to intercept Iraqi Scud attacks. Despite initial glowing reports from the Pentagon, a study by the General Accounting Office shows that only 9 percent of intercept attempts were reliably successful.

January 3,1993. Presidents Bush and Yeltsin sign START II, limiting deployed warheads on each side to 3,000-3,500.

May 1993. Secretary of Defense Aspin renames SDIO the Ballistic Missile Defense Organization (BMDO).

February 15, 1995. The House narrowly defeats the section of the Republican "Contract with America" requiring deployment of a nationwide missile defense as soon as practical.

November 1995. A report from the intelligence community declares that no country could threaten the US with a ballistic missile attack in the next 15 years.

March 1996. The "Defend America Act," which declares it US policy to build a limited missile defense by 2003 is introduced in Congress, but does not come to a vote due to the enormous projected cost of deployment, then estimated at $31-60 billion.

June 24, 1997. First fly-by test of the Boeing/TRW exoatmospheric kill vehicle for the NMD system. A lawsuit filed by a former TRW employee alleges that TRW misled defense officials about the results of the test.

March 21, 1997. Presidents Clinton and Yeltsin agree to a START III framework.

September 26, 1997. The US and Russia agree that the ABM Treaty includes Belarus, Kazakhstan and Ukraine.

February 1998. First report issued by commission chaired by retired Air Force Gen. Larry Welch on the status of US missile defense programs. The report is critical of BMDO’s efforts, finding a "rush to failure" schedule.

April 30, 1998. DoD selects Boeing as lead contractor for the NMD program.

July 1998. A commission chaired by Donald Rumsfeld (now secretary of defense) finds that the threat of a ballistic missile attack could emerge sooner than predicted in the 1995 intelligence estimate. Many experts criticize the commission, however, for emphasizing what could happen rather than what was likely to happen.

August 31, 1998. North Korea launches a Taepo Dong 1 missile over Japan, but the third stage fails to put its payload in orbit.

January 20, 1999. DoD requests more funds for NMD and announces the delay of the target date for achieving initial operating capability from 2003 to 2005, also moving the deployment decision date to June 2000.

March 1999. "The National Missile Defense Act of 1999" passes the Senate, while the House of Representatives approves a measure committing the US to deploy national missile defenses.

July 23, 1999. President Clinton signs the National Missile Defense Act of 1999, but lists four criteria he will use to make an ultimate deployment decision: threat, cost, technological status of NMD, and adherence to a renegotiated ABM Treaty.

September 1999. The Welch panel again concludes that the Pentagon’s approach is extremely high-risk after assessing the reconfigured NMD program.

June 13, 2000. The third Welch panel reports that NMD deployment by 2005 for Initial Operational Capability (IOC) remains high risk.

September 1, 2000. President Clinton decides not to proceed with deployment of the NMD system, citing the status of technology and concerns among the US allies and opposition from Russia and China. He defers an ultimate deployment decision to the next administration.

January 2001. President Bush affirms his plan to deploy a robust NMD system. Russian President Putin warns the US that the ABM Treaty bans NMD systems on both sides.

May 1, 2001. In a speech to the National Defense University, President Bush outlines his vision for a national security policy. In the speech, the president advocates an ambitious missile defense and moving beyond the ABM Treaty.

June 2001. The White House FY02 defense budget calls for a 57 percent increase for missile defense, up $3 billion to $8.3 billion.

June 13, 2001. Bush meets NATO leaders. Among the 19 NATO states, Spain, Hungary, Italy, Poland, Czech Republic, and Britain publicly signal some approval, to varying degrees, for NMD. France, Germany, and others remain vehemently against Bush’s plan, emphasizing the need to strengthen arms control regimes.

June 16, 2001. First Bush-Putin summit in Slovenia. Although a cordial meeting, the two leaders fail to reach concrete agreements on missile defense and the ABM Treaty.

July 14, 2001. The fourth intercept test (IFT-6) of the ground-based midcourse system successfully intercepts a mock warhead. Later reports find that this test, like others before it, was aided by the use of a homing beacon in the mock warhead.

December 3, 2001. In this test (IFT-7) the kill vehicle successfully intercepted the target.  One decoy balloon was used.  This test was a repeat of IFT-6.