Washington: Thursday`s shootings at two military installations in Chattanooga, Tennessee that left five people dead including the gunman is the latest in a series of attacks on military posts in the United States.
In December 2011, a controversial Senate report warned that American soldiers were under threat in their own country, targeted in particular by jihadist extremists. It recommended boosting security at military facilities.
Mental instability has also played a part in several of the attacks.
Here are the major deadly attacks in recent years:
January 7, 2015: Two people are killed, including the gunman, in a shooting at a military veterans clinic at Fort Bliss, a US Army post in El Paso, Texas.
April 2, 2014: A US soldier fires at least 35 rounds from his semi-automatic weapon on the Fort Hood US Army base in Texas, leaving three dead and 16 wounded. The gunman, who had been judged psychologically unstable, shoots himself dead.
Fort Hood is the world`s largest US military base, with at least 45,000 military and 9,000 civilian personnel.
September 16, 2013: Aaron Alexis, 34, kills 12 people and wounds eight others at the Washington Navy Yard, just two miles (three kilometers) from the US Capitol building, before being shot dead by officers.
Alexis worked for a sub-contractor, had a security clearance and could legally buy a gun, despite behavioral and psychiatric disorders.
November 5, 2009: Major Nidal Hasan, a US Army psychiatrist, kills 13 people and wounds more than 30 others at Fort Hood, in the deadliest mass shooting on a US military base.
Struck in the spine during the resulting firefight with security, Hasan is confined to a wheelchair. During the murder investigation, he declares he committed the assault to avenge the deaths of fellow Muslims. He is considered a "lone wolf" who supported terror network Al-Qaeda.
He is sentenced to death in 2013 but his case is expected to be considered by an appeals court.
June 1, 2009: A 24-year-old Muslim convert shoots at two soldiers outside a military recruitment center in Little Rock, Arkansas, killing one and wounding the other. The assailant, opposed to US military engagement in the Middle East, had spent some time in Yemen. He is sentenced to life in prison.