It would be "crazy" for the United States to shoot a few missiles at Syria for "cosmetic" purposes and not try to topple Bashar Assad's regime, Sen. John McCain says.

Many, including McCain, think President Barack Obama will fire cruise missiles to send Assad a message, but not attempt to actually change the course of the civil war, McCain said Wednesday on Fox News Channel's "On the Record."

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"You can't reconcile those two positions," McCain said. The situation has created a "very difficult position" for Obama, he added.

Lawmakers in both parties are divided; some think Obama is obligated to act after drawing a "red line" in 2012 that the United States would intervene if Syria used chemical weapons. Others fear even a symbolic attack would escalate tensions.

McCain visited Syrian rebels earlier this year and has been a lonely voice advocating for the United States to step up aid for the rebels with arms and training.

"America must lead, and America is not leading," McCain said.