Obama warned to keep Congress in the loop on Syria policy

Corker said he expected the committee to be "consulted directly before you make any significant changes to the nature and scope of U.S. engagement, including providing lethal assistance to opposition forces and particularly any use of U.S. armed forces."

The letter comes amid reports that U.S. forces are helping Jordanians train rebels who could eventually create a safe zone along the border in southern Syria. In addition, a United Nations expert is poised to enter Syria to investigate claims of chemical weapons use, which Obama has called a “red line” that would spark a U.S. response.

Former Secretary of State Hillary ClintonHillary Diane Rodham ClintonO’Malley tells Dems not to fear Trump FBI informant gathered years of evidence on Russian push for US nuclear fuel deals, including Uranium One, memos show Pelosi blasts California Republicans for supporting tax bill MORE and former Defense chief Leon Panetta previously recommended the United States arm the rebels. Obama has ruled against that so far out of concern that the weapons could end up in the hands of Islamist militants who could use them against U.S. interests.

Corker said he considered the administration's legal justifications for action in Libya two years ago to be “tenuous at best.” He has also expressed frustration with Secretary of State John KerryJohn Forbes KerryTrump's dangerous Guantánamo fixation will fuel fire for terrorists Tech beefs up lobbying amid Russia scrutiny Overnight Tech: Senate Dems want FCC chief recused from Sinclair merger | Tech rallies on Capitol Hill for DACA | Facebook beefs up lobbying ranks MORE's recent announcement of $60 million in direct aid to the rebels, telling The Hill that he was “a little disappointed that no heads up was given.”

Corker cautioned the administration that its actions in Syria should be dictated by national security interests.

“The situation in Syria is undoubtedly dire and worsening, and I may ultimately support U.S. involvement in this case. However, our response to this evolving situation must account fully for all of our national security interests, including the risk that U.S. military involvement, limited or otherwise, could trigger escalation that might threaten our regional allies,” he said.