Sen. John McCain, Arizona Republican, on Tuesday derided President Obama’s attack on GOP presidential nominee Mitt Romney over his remark in Monday night’s debate that the U.S. Navy is smaller now than at any time since World War I as “cheap shots.”

“I don’t understand why the president wants to take these kind of cheap shots — bayonets and horses, what’s that all about?” Mr. McCain said on MSNBC’s “Morning Joe.” “You know, when I debated then-Senator Obama, I didn’t criticize or belittle his lack of experience on national security issues. And he seemed to take these kind of cheap shots … I kind of resent it.”

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After Mr. Romney pointed out that the Navy is smaller now than at any point since 1917 and the Air Force is “older and smaller” than at any time since 1947, Mr. Obama fired back with one of the more memorable lines from the final debate.

“You mentioned the Navy, for example, and that we have fewer ships than we did in 1916,” Mr. Obama replied.

“Well, Governor, we also have fewer horses and bayonets, because the nature of our military’s changed. We have these things called aircraft carriers, where planes land on them. We have these ships that go underwater, nuclear submarines. And so the question is not a game of Battleship, where we’re counting ships.”

Mr. McCain went on to call the comments “small ball.” But the line was inarguably memorable: #horsesandbayonets was still trending on Twitter on Tuesday morning.