President Obama's announcement on the July start of a U.S. troop withdrawal from Afghanistan comes nearly a decade after the U.S.-led military operation began.

War on Terror

October 7, 2001 – Three weeks after the September 11 terror attacks on the United States, President George W. Bush announces Operation Enduring Freedom, with U.S. military strikes against al-Qaida terrorist camps and Taliban bases in Afghanistan. In an address to the American people, Mr. Bush said the Taliban will pay a price for not meeting U.S. demands to hand over the al-Qaida leadership.

November 13, 2001 – Northern Alliance and U.S. forces enter the Afghan capital, Kabul, forcing the Taliban to retreat and flee south toward Kandahar province.

December 5, 2001 – The United Nations sponsors a conference in Germany with major Afghan factions. They sign an accord that lays out a road map for political development in post-war Afghanistan. The Bonn Agreement installs Hamid Karzai as Afghan interim administration head and creates an international peacekeeping force to maintain security in Kabul.

December 13, 2001 — In eastern Afghanistan, the United States intensifies its bombing campaign in pursuit of al-Qaida fighters hiding in the hills of Tora Bora.

Reconstruction Efforts

March 2, 2002 – U.S. forces launch their biggest ground offensive yet, Operation Anaconda, against several hundred al-Qaida and Taliban fighters in mountainous eastern Afghanistan.

June, 2002 — A grand council, known as a loya jirga, elects Hamid Karzai to lead Afghanistan's transitional administration. The body will draft a new constitution and lead the way for elections in the next 18 months.

November, 2002 – The U.S. army creates military-civilian units, called provincial reconstruction teams, or PRTs, as part of stabilization efforts. PRTs were designed to help deliver basic services including security, health care and education. The city of Gardez is the first PRT site, followed by Bamiyan, Kunduz, Mazer-e-Sharif, Kandahar and Herat.

NATO Moves Outside Europe

May 1, 2003 – U.S. Defense Secretary Donald Rumsfeld declares an end to major combat, in a briefing with reporters in Kabul. Eight thousand U.S. troops are stationed in Afghanistan at the time. Rumsfeld spoke as President Bush made a similar declaration on the aircraft carrier, USS Abraham Lincoln.

August 8, 2003 – NATO assumes security in and around Kabul, the organization's first commitment outside of Europe. This gives the alliance a leadership role in the United Nations-mandated International Security Assistance Force, known by the acronym ISAF.

Constitution and Democratic Elections

January, 4, 2004 – A loya jirga adopts a new Afghan constitution. The move marks a major step toward holding the country's first free elections in more than two decades.

October 9, 2004 – Mr. Karzai becomes the country's first democratically elected president, winning 55 percent of the vote.

October 29, 2004 – Osama bin Laden releases a videotape to Arab television network al-Jazeera four days before the U.S. presidential election. In the video, the al-Qaida leader tells Americans their security does not depend on who is elected or al-Qaida, but on U.S. government policies.

May 23, 2005 – During President Karzai's visit to Washington, he and President Bush sign a joint declaration, re-emphasizing the strategic partnership between the United States and Afghanistan.

September 18, 2005 – Afghanistan holds its first parliamentary elections, choosing 249 legislators and delegates to 34 provincial councils including, for the first time in Afghanistan, women. Nearly 600 women are among the six thousand candidates. The election is considered a key test of Afghanistan's ability to establish a functioning democracy.

Fighting Intensifies

July, 2006 – Fighting between Taliban and al-Qaida fighters and Afghan government forces intensifies.

November 28, 2006 – Afghanistan dominates the NATO summit in Riga, Latvia.

May 13, 2007 – The Taliban's top military commander, Mullah Dadullah, is killed in a U.S.-led operation in southern Afghanistan's Helmand province. He was widely regarded as one of the militant group's most capable and ruthless commanders.

June 12, 2008 – The international community pledges more than $20 billion in aid to Afghanistan at a donors' conference in Paris.

August 22, 2008 – A coalition airstrike in Herat province's Shindand district kills civilians and militants. A U.S. military investigation concluded that more than 30 civilians died, not five as the U.S. military initially insisted.

U.S. Troop Surge

February 17, 2009 — President Obama approves a nearly 50 percent increase in the number of U.S. troops in Afghanistan. Pentagon officials say the total will come to 17,000, in addition to the 38,000 U.S. troops already in Afghanistan. And they say all the new troops will go to Afghanistan's troubled southern region, near the border with Pakistan.

March 27, 2009 – President Obama announces a new strategy, linking success in Afghanistan to a stable Pakistan. He said the goal is to disrupt, dismantle and defeat al-Qaida in Pakistan and Afghanistan, and to prevent its return to either country in the future.

May 11, 2009 – Defense Secretary Gates replaces the top U.S. military commander in Afghanistan, General David McKiernan, with General Stanley McChrystal. Gates said it was time for fresh thinking and fresh eyes on the war in Afghanistan.

July 2009 — U.S. Marines launch the first major offensive operation (Operation Khanjar, Strike of the Sword) under President Obama's revamped strategy to defeat an increasingly violent Taliban insurgency.

New U.S. Strategy

December 1, 2009 – President Obama announces his new strategy for winning the war in Afghanistan, which involves sending 30,000 more U.S. troops to the country by the summer of 2010. The added troops will join an estimated 68,000 U.S. service members and tens of thousands of allied forces in Afghanistan.

June 23, 2010 – President Obama accepts the resignation of his top commander in Afghanistan, General McChrystal, and names General David Petraeus to replace him.

November 2010 – At a NATO summit in Lisbon, NATO and Afghanistan sign an agreement marking the Atlantic alliance's commitment to the war-torn nation after it ends combat operations, ostensibly by the end of 2014.

U.S. Enemy Number One Is No Longer

May 1, 2011 — President Obama tells the world that Osama bin Laden has been killed by U.S. special forces following an assault on his hideout in Abbottabad, Pakistan.

June 22, 2011 – President Obama announces his decision on the size and pace of a U.S. troop drawdown in Afghanistan.