Three weeks ago, the U.S. Army awarded Purple Hearts to two soldiers who were wounded in an attack by a gunman on a military recruiting center. One of them, Pvt. William Long, received the award posthumously after being killed in the attack. The other, Pvt. Quinton Ezeagwula, was wounded numerous times but survived.

The June 1, 2009, attack in Little Rock, Ark., was recalled by many following the shootings last week at a military recruiting center and naval reserve installation in Chattanooga, Tenn., that killed four Marines and a sailor: Gunnery Sgt. Thomas Sullivan, 40; Staff Sgt. David Wyatt, 35; Sgt. Carson A. Holmquist; Lance Cpl. Squire D. “Skip” Wells, 21; and Petty Officer 2nd Class Randall Smith, 26.

All five were at the naval reserve center, one of two locations targeted by the shooter, Mohammad Youssef Abdulazeez, 24, who was also killed.

The attacks are evidence, some say, that the Pentagon should end its long-held restrictions on U.S. service members arming themselves while at military facilities. Law enforcement officials said Monday that they had recovered a privately-owned pistol at the reserve center following the shootout that may have been carried by one of the deceased Marines, but they would not have been allowed to do so.

Defense Secretary Ashton B. Carter called on Friday for “immediate steps” to be taken to enhance force protection following the Chattanooga shooting, but arming troops was not one of them. Mark Wright, a spokesman at the Pentagon, said that the Marine Corps chose to close all recruiting offices within 40 miles temporarily, instruct some recruiters not to wear uniforms and to boost security at recruiting stations to force protection level Charlie, indicating an increased terrorist threat exists.

The Army also increased its security at recruiting centers to force protection level Charlie, and the Navy opted to have more random searches at facilities and coordinate more closely with law enforcement.

Pentagon officials said that Carter also called for a review by the services to determine how security can be improved, with recommendations due back to him within a few days.

Carter, asked about the review Sunday while flying from Washington to Israel, did not say whether he is considering arming U.S. troops while on base Stateside.

“We took some steps on Friday that seemed immediately advisable,” the secretary told reporters, without elaborating. “I’ve asked the services to quickly, but in a comprehensive way, assess additional things that they might recommend.”

Pressure is mounting to arm troops. Sen. Ron Johnson (R.-Wis.) said Friday he would introduce legislation that would get rid of rules preventing service members from being armed at military installations. Sen. John McCain (R.-Ariz.), chairman of the Senate Armed Services Committee, and Rep. Mac Thornberry (R.-Tex.), chairman of the House Armed Services Committee, also called Friday for the Pentagon to do more to protect troops.

“Long before the Chattanooga attack, we had been working to clarify a post commander’s authority to allow carrying of personal firearms,” McCain and Thornberry said in a joint statement. “This year’s National Defense Authorization Act will reflect that work.  Together, we will direct the Pentagon to end the disconnect between the threats our war fighters and their families face and the tools they have to defend themselves.”

The independent Marine Corps Times captured the sentiment among many rank-and-file Marines on the cover of its newspaper on Monday. The headline: “The call to arm all Marines — now.” It was greeted by readers on Facebook with widespread agreement.

In the 1990s, the Pentagon restricted who can carry weapons at military facilities, ostensibly to make them safer by allowing only military police to carry weapons in most situations.

There is some disagreement over where the policy originated. Some have blamed former President Clinton, citing a 1993 Army directive that limited the use of firearms on military bases. But it actually traces back a little farther. A 1992 Defense Department directive issued during President George H.W. Bush’s administration addressed the issue and provided the Pentagon’s rationale for limiting who carried firearms in the United States.

“The authorization to carry firearms shall be issued only to qualified personnel when there is a reasonable expectation that life or DoD assets will be jeopardized if firearms are not carried,” the directive said. “Evaluation of the necessity to carry a firearm shall be made considering this expectation weighed against the possible consequences of accidental or indiscriminate use of firearms. DoD personnel regularly engaged in law enforcement or security duties shall be armed.”

The issue has come up after numerous shootings on military bases, including the 2009 and 2014 attacks at Fort Hood, Tex., and the 2013 mass shooting at the Washington Navy Yard.

This post has been updated to reflect that no blanket directive was issued telling Marine recruiters not to wear their uniforms, following the Chattanooga attack. Some commanders in specific locations may have done so, according to Marine Corps Recruiting Command.