During the first phase of its history, the United States tried to isolate itself from foreign conflicts. In the 1900s, however, the United States participated in two world wars, became a global superpower, and eventually became a major proponent of world trade.
World War I begins.
World War I ends.
The U.S. declares the war with Germany to be at and end.
End of World War II. The U.S. is a founding member of the United Nations.
The U.S. and 11 other nations sign the North Atlantic Treaty, forming NATO.
President Nixon orders a halt to offensive operations in North Vietnam on Jan. 15 and representatives from all sides sign a peace pact, ending the longest war in U.S. history. The last American troops depart by March 1973.
The Berlin Wall comes down, marking the end of the Cold War.
A U.S.-led multinational force attempts to restore order to war-torn Somalia so that food can be delivered and distributed within the famine-stricken country.
During the Bosnian civil war, which begins shortly after the country declares independence in 1992, the U.S. launches air strikes on Bosnia to prevent ethnic cleansing. It becomes a part of NATO's peacekeeping force in the region.
The U.S. is a founding member of the World Trade Organization (WTO), formed to monitor and promote world trade.
Yugoslavia's province of Kosovo erupts in war in the spring of 1999. A U.S.-led NATO force intervenes with air strikes after Slobodan Milosevic's Serbian forces uproot the population and embark on a plan of ethnic cleansing of Kosovo's ethnic Albanian population.
On Aug. 31, President Obama announces the end of U.S. combat missions in Iraq.
Operation New Dawn begins on Sep. 1. A U.S. transitional troop force will remain in Iraq, tasked with the mission: "advising and assisting Iraq's Security Forces, supporting Iraqi troops in targeted counterterrorism missions, and protecting our civilians."
On May 2, 2011 (May 1 in the U.S.), U.S. troops and CIA operatives shot and killed Osama bin Laden in Abbottabad, Pakistan.
May 1, 2012, President Obama and President Karzai signed the Enduring Strategic Partnership Agreement between the Islamic Republic of Afghanistan and the United States of America. The Agreement provides for the possibility of U.S. forces in Afghanistan after 2014, for the purposes of training Afghan Forces and targeting the remnants of al-Qaeda. Afghanistan will be a “Major Non-NATO Ally” and as such, the U.S. will support the training, equipping, advising and sustaining of Afghan National Security Forces, and social and economic assistance.
According to the Department of Defense, 6,097 targets were damaged or destroyed as of April 23, 2015. The strikes were conducted as part of Operation Inherent Resolve, an undertaking meant to eliminate the Islamic State of Irag and the Levant (ISIL) terrorist group and the threat they pose to Iraq, Syria, the region, and the wider international community. Coalition nations conducting airstrikes in Iraq include the United States, Australia, Belgium, Canada, Denmark, France, Jordan, the Netherlands and the United Kingdom; coalition nations conducting airstrikes in Syria include the United States, Bahrain, Canada, Jordan, Saudi Arabia and the United Arab Emirates.