The Thursday attack that killed 12 people and wounded 31 at Fort Hood, Texas appears to be the deadliest mass shooting at a US military base in modern history.
Officials at Fort Hood, the largest US military base in the world, said a soldier opened fire in a busy processing center where troops go before being deployed to Iraq and Afghanistan.
In May a US Army soldier was arrested after a shooting spree at Camp Liberty in the Iraqi capital Baghdad that killed five people and wounded three more.
That attack occurred at a clinic for soldiers suffering from war-related stress.
In 2005, in what was believed to be the first recorded case of "fragging" in Iraq, a US Army sergeant was charged with premeditated murder in the deaths of two US officers who were killed in an explosion at their base near Tikrit.
And in March 2003, just days after US troops poured over the border into Iraq, an American soldier was detained after grenades thrown into three tents exploded at a US base in Kuwait, killing one soldier and wounding another 13.
Fatal attacks on military bases in the United States are rare. In May 2007 five suspected Islamic radicals were arrested by the FBI after a 16-month sting operation and eventually found guilty of plotting to kill "as many soldiers as possible" at the Fort Dix army base in New Jersey.
The men, three Albanians from Macedonia, a Palestinian from Jordan and a man born in Turkey, were all living in the Philadelphia area when they were arrested.
The Fort Hood shooting is among the deadliest in the United States, but other mass shootings in Texas have also made the list, including the notorious rampage in 1966 by student Charles Whitman, who gunned down 14 people from the observation deck of a tower on the campus of the University of Texas, Austin before he himself was shot dead by police.
In 1991, in what was then the nation's worst mass shooting on record, a gunman drove his pickup truck into a crowded cafeteria in Killeen, Texas, the city adjacent to Fort Hood, and began firing indiscriminately, killing 22 people before he himself was found dead.