The White House said Thursday it would send military assistance to the Syrian opposition after concluding that Syrian President Bashar Assad has crossed President Obama's so-called red line on chemical weapons.
Deputy National Security Adviser for Strategic Communications Ben Rhodes told reporters the president has ruled out putting U.S. boots on the ground, however, and remains unconvinced that a no-fly zone to protect rebel-held areas is workable.
Rhodes did not make it clear what types of military assistance would be provided and did not use the word "weapons" when asked directly whether arms would be delivered to rebel groups.
"I cannot detail for you all the types of that support for a variety of reasons, but again suffice to say, this is going to be different in both scope and scale in terms of what we are providing to the [opposition] than what we were providing before.”
Rhodes did not announce a no-fly zone over Syria, but said it had not been ruled out.
“We have not made any decisions to pursue a military operation such as a no-fly zone,” he said.
U.S. officials told The Wall Street Journal late Thursday that a plan to arm rebels also calls for a limited no-fly zone that would stretch up to 25 miles into Syria and be enforced from Jordan.
Rhodes said the administration believes as many as 150 people have been killed in chemical weapons attacks in Syria, and that there is no evidence they have been used by opposition groups.
The president did not address the administration's determination of chemical weapons use or decision to extend new military aid to the rebels while speaking at an LGBT Pride event Thursday evening at the White House.
Two Republicans who have repeatedly called for stronger actions on Syria criticized the White House for not announcing a no-fly zone over Syria.
Sens. John McCain (R-Ariz.) and Lindsey Graham (R-S.C.) said Obama needed to do more than just supply weapons to the rebels in Syria.
“Every bone in my body knows that simply supplying weapons will not change the equation,” McCain said on the Senate floor. “The president better understand that just supplying weapons will not change the balance.”
Rhodes said that a no-fly zone in Syria was much more complex than the one established during the 2011 conflict in Libya, and that it would include "huge costs."
He also said there was no guarantee that it would improve the situation on the ground, because many of the opposition and regime forces are co-mingled in the same areas. “The notion you can solve the very deeply rooted challenges on the ground in Syria from the air are not immediately apparent,” he said.
Other Republicans accused the administration of waiting too long to announce tougher actions on Syria.
A spokesman for Speaker John Boehner (R-Ohio) said it was "long past time to bring the Assad regime’s bloodshed in Syria to an end."
He said Obama should consult with Congress as he examines his options before taking any action.
Rep. Mike Rogers (R-Mich.), the chairman of the House Intelligence Committee, said he was pleased with the declaration.
He said the U.S. should assist Turkey and the Arab League in creating safe zones in Syria from which the U.S. and its allies can train and arm vetted rebel groups.
"These efforts have the potential of turning the tide once and for all against the Assad regime to deliver a peace negotiation," he said. "Then the United States would have the credibility it needs for a seat at the table during the transition to a post-Assad Syria.”
"We will be consulting with Congress on these matters in the coming weeks," Rhodes said.
"Put simply, the Assad regime should know that its actions have led us to increase the scope and scale of assistance that we provide to the opposition."
Rep. Eliot Engel (D-N.Y.), one of the first Democrats to call for arming the rebels, said the administration should act immediately.
"In using chemical weapons, Assad has committed a war crime against his own people," said Engel, who introduced legislation authorizing weapons to be sent back in March.
"What more does the civilized world need in order to come to the aid of the Syrian people who want to rid themselves of this monster? The president's 'red line' has clearly been crossed, and it is crystal clear that the United States must provide appropriate arms to those in Syria fighting for their lives and freedom. Further delay is not an option."
—Jeremy Herb, Justin Sink and Jordy Yager contributed
This story was posted at 4:58 p.m. and last updated at 9:36 p.m.