The general nominated to be the top Marine said he would not dismiss the notion of arming recruiters after last week's attacks in Chattanooga, Tenn., but "that's probably the most extreme measure we could do."

Lt. Gen. Robert Neller, in testimony before the Senate Armed Services Committee on Thursday, also warned of "second and third order effects, particularly on recruiters and their access for things they need to do. There are some practical matters that need to be worked out."

He was responding to a question from Sen. Joe Manchin, D-W.Va., following the deaths of four Marines and a sailor when a gunman attacked a reserve center and a recruiting office. Service members on U.S. bases, in most cases, cannot carry firearms unless they are a member of base security, and last week's shootings reignited the debate.

Recruiters typically work in leased commercial space and must adhere to state laws when it comes to carrying firearms. Experts point out that arming recruiters complicates their efforts to access schools, where a good deal of recruiting takes place. There's also the issue of additional training for service members and the possibility of accidental discharges.

Neller pointed out that U.S. Northern Command has put out increased security measures, which he said "I'm not going to discuss here."

"[The measures] I believe are prudent," he said. "There are some physical things they will look at."