For the second time in just over five years, President Obama paid tribute this week to fallen soldiers at a memorial service at the Fort Hood Army base in Texas, where a lone gunman went berserk last week, killing three people and wounding 16 others. Witnesses and relatives of the wounded said that Spc. Ivan Lopez’s rampage began when he walked into a human-resources office and requested a leave of absence, but was told to come back the next day. Lopez left, but returned moments later with an unauthorized semi-automatic handgun and opened fire, killing two soldiers. He then walked outside and indiscriminately shot at other soldiers, before turning the gun on himself when confronted by an armed military police officer.

Army officials acknowledged that Lopez—who served as a truck driver in Iraq in 2011—was being evaluated for post-traumatic stress disorder and was taking medications for anxiety, depression, and sleep disorders. But he had not shown any signs of being a threat to himself or others, officials said.

“Not even the most powerful military force on earth can insulate itself from the nation it serves,” said The Boston Globe in an editorial. In a society “flooded with firearms,” angry soldiers, disgruntled employees, and disturbed civilians can easily get their hands on a weapon. Lopez purchased his firearm legally at a local Guns Galore, the same store where Nidal Hasan purchased the weapon he used to gun down 12 soldiers and a civilian at Fort Hood in 2009. No amount of extra base security can prevent these kinds of tragedies on Army bases or anywhere when access to guns is so recklessly unfettered.

But the troops would have had a fighting chance if they’d been allowed to carry weapons on base, said John Lott in Current Pentagon policy states that the only people allowed to be armed on U.S. bases are military police officers. But mass shooters always “seek out venues where they don’t have to worry about victims defending themselves,” which means thousands of troops serving here in the U.S. are little more than “sitting ducks.” With more than 11 million citizens legally allowed to carry concealed weapons today, why can’t our soldiers?