The Obama administration said on Tuesday it knew in advance of Republican Senator John McCain's trip to Syria, a visit that raised anew the question of whether the United States will intervene in a civil war that has raged for over two years.
But U.S. officials had little to say about the trip by McCain, an outspoken advocate for U.S. military aid to the rebels fighting President Bashar al-Assad.
President Barack Obama has repeatedly shied away from U.S. involvement in the conflict, which has claimed 80,000 lives, although he has kept all options on the table. The Obama administration has sent food and medical supplies to Assad's opponents.
"We were aware, of course, that Senator McCain was going to make this trip," White House spokesman Jay Carney said. "And we look forward to speaking with Senator McCain upon his return to learn more about the trip."
At the State Department, spokesman Patrick Ventrell noted that members of Congress often travel abroad and make their policy positions known. "I don't have a particular reaction to the trip one way or another," Ventrell said.
McCain's office said his visit was organized by the Syrian Emergency Task Force (SETF), a non-profit group that backs the Syrian opposition and is based in the United States. The Republican senator crossed into northern Syria from the country's border with Turkey on Monday and stayed there several hours in a surprise visit.
McCain saw General Salim Idris, the leader of the Supreme Military Council of the Free Syrian Army coalition of rebel groups, as well as 18 commanders of Free Syrian Army battalions from all of Syria, the SETF website said.
"While meeting with Senator McCain, General Idris and FSA commanders asked that the United States increase its aid to the Free Syrian Army in the form of heavy weapons, a no-fly zone, and air strikes on Hezbollah," the SETF website said, referring to the Shi'ite militant group in Lebanon that backs Assad.
McCain's trip came as a Reuters/Ipsos online poll on Tuesday found only 12 percent of Americans said they were in favor of U.S. intervention in Syria as opposed to 58 percent who are against it.
Obama has resisted pressure to deepen U.S. involvement in Syria, wary of getting the United States embroiled in another war just as American troops are preparing to withdraw from Afghanistan.
U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov have been trying to organize an international peace conference on Syria. But Russia said on Tuesday that the European Union's failure to renew an arms embargo on Syria would undermine the chances for peace talks.
McCain made a similar visit to Libya early in that country's conflict, traveling to rebel-held Benghazi in April 2011 after Western powers had begun their intervention in the uprising against then-Libyan leader Muammar Gaddafi.