Senate Foreign Relations Committee

Biden was a longtime member of the U.S. Senate Committee on Foreign Relations.

Biden voted against authorization for the Gulf War in 1991, siding with 45 of the 55 Democratic senators; he said the U.S. was bearing almost all the burden in the anti-Iraq coalition.

In 1997, Joe Biden became the ranking minority member and chaired the committee in January 2001 and from June 2001 to 2003. When Democrats retook control of the Senate after the 2006 elections, Biden again assumed the top spot on the committee. He was generally a liberal internationalist in foreign policy. He collaborated effectively with important Republican senators such as Richard Lugar and Jesse Helms and sometimes went against elements of his own party. Biden was also co-chairman of the NATO Observer Group in the Senate. A partial list covering this time showed Biden meeting with 150 leaders from nearly 60 countries and international organizations. He held frequent hearings as chairman of the committee, as well as many subcommittee hearings during the three times he chaired the Subcommittee on European Affairs.

Biden voted against authorization for the Gulf War in 1991, siding with 45 of the 55 Democratic senators; he said the U.S. was bearing almost all the burden in the anti-Iraq coalition.

Biden became interested in the Yugoslav Wars after hearing about Serbian abuses during the Croatian War of Independence in 1991.

Once the Bosnian War broke out, Biden was among the first to call for the "lift and strike" policy of lifting the arms embargo, training Bosnian Muslims and supporting them with NATO air strikes, and investigating war crimes. The George H. W. Bush administration and Clinton administration were both reluctant to implement the policy, fearing Balkan entanglement. In April 1993, Biden spent a week in the Balkans and held a tense three-hour meeting with Serbian leader Slobodan Milosevic. Biden related that he had told Milosevic, "I think you're a damn war criminal and you should be tried as one." Biden wrote an amendment in 1992 to compel the Bush administration to arm the Bosnians, but deferred in 1994 to a somewhat softer stance the Clinton administration preferred, before signing on the following year to a stronger measure sponsored by Bob Dole and Joe Lieberman. The engagement led to a successful NATO peacekeeping effort. Biden has called his role in affecting Balkans policy in the mid-1990s his "proudest moment in public life" related to foreign policy.

In 1998, Congressional Quarterly named Biden one of "Twelve Who Made a Difference" for playing a lead role in several foreign policy matters, including NATO enlargement and the successful passage of bills to streamline foreign affairs agencies and punish religious persecution overseas. In 1999, during the Kosovo War, Biden supported the NATO bombing campaign against Serbia and Montenegro, and co-sponsored with John McCain the McCain-Biden Kosovo Resolution, which called on President Clinton to use all necessary force, including ground troops, to confront Milosevic over Serbian actions in Kosovo. In 2016, Biden paid a state visit to Serbia where he met with Serbian president Aleksandar Vucic and expressed his condolences for the civilian victims of the bombing campaign.

Biden was a strong supporter of the 2001 war in Afghanistan, saying, "Whatever it takes, we should do it."

As head of the Senate Foreign Relations Committee, Biden said in 2002 that Saddam Hussein was a threat to national security and there was no option but to "eliminate" that threat. In October 2002, he voted in favor of the Authorization for Use of Military Force Against Iraq, approving the U.S. invasion of Iraq. More significantly, as chair of the committee, he assembled a series of witnesses to testify in favor of the authorization. They gave testimony grossly misrepresenting the intent, history of and status of Saddam and his Sunni government, which was an openly avowed enemy of al-Qaida, and touting Iraq's fictional possession of weapons of mass destruction.

While he eventually became a critic of the war and viewed his vote and role as a "mistake", he did not push for U.S. withdrawal. He supported the appropriations to pay for the occupation, but argued repeatedly that the war should be internationalized, that more soldiers were needed, and that the Bush administration should "level with the American people" about the cost and length of the conflict. By late 2006, Biden's stance had shifted considerably, and he opposed the troop surge of 2007, saying General David Petraeus was "dead, flat wrong" in believing the surge could work. Biden instead advocated dividing Iraq into a loose federation of three ethnic states. In November 2006, Biden and Leslie H. Gelb, President Emeritus of the Council on Foreign Relations, released a comprehensive strategy to end sectarian violence in Iraq. Rather than continuing the present approach or withdrawing, the plan called for "a third way": federalizing Iraq and giving Kurds, Shiites, and Sunnis "breathing room" in their own regions.:572 to 573 In September 2007, a non-binding resolution endorsing such a scheme passed the Senate, but the idea was unfamiliar, had no political constituency, and failed to gain traction. Iraq's political leadership denounced the resolution as de facto partitioning of the country, and the U.S. Embassy in Baghdad issued a statement distancing itself from it

In March 2004, Biden secured the brief release of Libyan democracy activist and political prisoner Fathi Eljahmi, after meeting with leader Muammar Gaddafi in Tripoli. In May 2008, Biden sharply criticized President George W. Bush for his speech to Israel's Knesset, where he suggested some Democrats were acting the way some Western leaders did when they appeased Hitler in the run-up to World War II. Biden said, "This is bullshit. This is malarkey. This is outrageous. Outrageous for the president of the United States to go to a foreign country, sit in the Knesset ... and make this kind of ridiculous statement ... Since when does this administration think that if you sit down, you have to eliminate the word 'no' from your vocabulary?" He later apologized for using the expletive.