He went to meet with military leaders of the rebels who are fighting to run off President Bashar Al-Assad and his regime.
One woman who set up his visit said he wanted to show the rebel forces the U.S. has not abandoned them, and the American people support their war. American diplomats are trying to get rebel forces to a negotiating table, while Russians are doing the same with the Syrian government.
McCain wants the U.S. to first implement a no-fly zone over Syria to change the situation on the ground.
Following his visit, opposition fighters could soon have more support. Late Monday night, the European Union voted to allow member nations to ship weapons to Syria's outgunned rebels. Britain and France had pushed the European Union to end the ban on weapons shipments, although neither country has immediate plans to start arming the rebels.