House appropriators unveiled a $570 billion Defense spending bill on May 29 that prohibits the Barack Obama administration from drastically expanding its assistance to the Syrian opposition without first getting Congress to sign off.

The restrictive language comes as the White House and the Senate Armed Services Committee have been indicating a desire for stepped-up US support for vetted rebel forces, perhaps by shifting training from the CIA to the Department of Defense. The House bill serves as a reminder that there's little appetite, especially in the Republican-controlled House, for any policy change that could pull the United States into another war in the region.

"The president … has indicated he's willing to help the constructive elements of the opposition, and we will do that," Rep. Jim Moran, D-Va., a member of the House Appropriations panel on Defense, told Al-Monitor. "But we're doing that under some serious restrictions."

The bill is the first under the Defense appropriations panel's new chairman, Rep. Rodney Frelinghuysen, R-N.J., who took over after the death last year of Rep. Bill Young, R-Fla. Frelinghuysen has expressed skepticism about stepped-up US involvement in the Syrian civil war, and indicated last year that he would oppose President Obama's request to authorize military strikes if it ever came to a vote.