The U.S. could hit Syria with three days of missile strikes, perhaps beginning Thursday, in an attack meant more to send a message to Syrian President Bashar al-Assad than to topple him or cripple his military, senior U.S. officials told NBC News on Tuesday. -snip- But Sen. John McCain, R-Ariz., an influential voice on military matters, pressed the administration to go further, calling for the U.S. and its allies to provide weapons to "the resistance on the ground." "The important part of this whole situation is, is this just going to be just a retaliatory strike that has no lasting...