WASHINGTON (AP) ― With peace talks failing, Syria’s government on the offensive and moderate rebels pushed aside by al-Qaida-linked militants, the Obama administration is struggling for new ideas to halt a savage civil war.

Extending beyond Syria, the crisis is also an accelerating national security threat to the United States, officials say. And that, in part, has led to a fresh look at previously shelved ideas, including more robust assistance to Western-backed rebels.

Officials also have looked at newer, more far-reaching options, including drone strikes on rebel factions who might aspire to attack the United States ― though such strikes are seen as unlikely for now.

Obama has yet to approve any policy shift. His top aides plan to meet at the White House before week’s end to examine options. And last week, intelligence chiefs from the U.S. and several other countries met in Washington.

American officials face the same constraints as before in the three-year civil war, including concern that lethal assistance could end up in the hands of extremists. And then there also is President Barack Obama’s own distaste for military action.

White House spokesman Jay Carney said Tuesday, “We have to examine what the alternatives some might be proposing are and whether they’re in our national security interest.” He added that the administration also was concerned about whether increased intervention could lead to “unintended consequences.”

A Western official said last week‘s intelligence meeting indicated there was new motivation to see what more could be done, including strengthening the moderate opposition and increasing humanitarian assistance.

The renewed focus has been sparked in part by the apparent impasse in the Geneva peace talks and by increasing concerns about the potential terrorist threat emanating from Syria, according to the official, who was not authorized to discuss the matter by name and spoke only on condition of anonymity.

In recent weeks, Obama’s senior national security aides have also delivered warnings about extremist havens in Syria, and about Americans and other Westerners joining the fight and being radicalized.

“Syria has become a matter of homeland security,” Homeland Security Secretary Jeh Johnson said this month.

In separate testimony before Congress, National Intelligence Director James Clapper estimated there were about 26,000 extremists in Syria, including around 7,000 foreigners, in an insurgency encompassing 75,000 to 110,000 fighters. Jabhat al-Nusra, for example, one of the most powerful rebel factions, has “aspirations” for attacks on the United States, he said.

By any account, the current U.S. policy of sending limited military aid for Syria‘s moderate opposition coupled with support for U.N.-brokered peace talks between the rebels and Syrian President Bashar Assad’s government isn‘t working.

Scenes of emaciated children leaving the besieged city of Homs last week underscored the desperate plight of many Syrians. A second round of Geneva negotiations ended last weekend with little promise for a future breakthrough and with fresh American frustrations with Russia, which is Assad’s most powerful military and diplomatic supporter.

The administration concedes Assad‘s hold on power has strengthened.

For Obama, Syria presents no easy answers. After more than a decade of fighting in Afghanistan and Iraq, he has desperately sought to avoid embroiling the nation in another deadly and inconclusive war. He backed away last year from his threat to take military action in response to a Syrian chemical weapons attack when it became clear Congress would not vote its approval.

Even options short of direct strikes pose difficulties.

U.S. officials say grounding Assad’s air force by enforcing a no-fly zone in Syria would require a large-scale attack on Syria‘s advanced air defense systems. Military support for the opposition continues in the form of small weapons and ammunition. But proposals for sending more powerful weaponry still raise fears that it could fall into the hands of extremist rebels groups, which are melding with moderate rebels.