BEIRUT — Syria warned the Obama administration Monday not to extend its air war against the Islamic State into Syria, as the militants celebrated another key victory over government forces in the north of the country.
The warning came a day after the group overran a major air base in north-central Syria, putting the Islamic State in full control of Raqqah province, where American photojournalist James Foley was held for much of his captivity and where his beheading last week is thought to have occurred.
Raqqah also was the site of a failed rescue attempt this summer in which Delta Force commandos sought to snatch Foley and a group of other Americans held by the Islamic State from a prison east of Raqqah, said U.S. officials and witnesses in the area.
The capture of Tabqa airfield Sunday was the latest in a string of recent military successes for the extremist fighters, who have been consolidating their hold across northern Syria even as U.S. airstrikes launched earlier this month temper the group’s expansion in northern Iraq.
U.S. officials have not ruled out pressing the airstrikes into Syria, telling reporters last week that the United States would not be restricted by “geographic boundaries” when confronting the militants.
On Monday, the White House said President Obama has not decided whether to pursue military action in Syria, but it would not say whether he has been presented with any specific options.
White House press secretary Josh Earnest said “entire wings” of the Pentagon are “dedicated to making sure the president has a range of plans and options that they can present to him when — if and when necessary.”
As the administration considered possible military action in Syria, Obama last weekend authorized reconnaissance flights with manned and unmanned aircraft over potential Islamic State targets, a senior defense official said.
The authorization was in response to a request by the military’s Central Command. Officials said there has been no strike authorization, but the aerial intelligence-gathering is expected to provide a much better picture inside Syria than current satellite images and projections from outside Syrian airspace from flights near the country’s borders.
Earnest said that the current situation is different from last year’s proposed attacks against the Syrian government that Obama canceled after Congress rejected them. The administration has said that Obama has the constitutional authority to act to protect U.S. citizens such as those held hostage by the Islamic State in Syria.
On Monday, Syrian Foreign Minister Walid al-Moualem signaled that Damascus would not tolerate unilateral U.S. strikes against the extremists even in areas of the country the government no longer controls.
Fighting terrorism, Moualem said, should be done in cooperation with the Syrian government, “not through transgression against countries’ sovereignty.”
“Any breach of Syrian sovereignty by any side constitutes an act of aggression,” he added, speaking at a news conference in Damascus, according to the official Syrian Arab News Agency.
The Syrian government has long sought to use the extremists’ expanding influence as a means to restore U.S. recognition for the discredited regime, promising to act as partners in the fight against terrorism in return for an end to American support for the more-moderate rebels seeking to topple President Bashar al-Assad.
Moualem appeared to open the door to a joint effort to fight the extremists, but he said the Syrian government would have to be consulted first. “They are welcome,” he said when asked whether the United States could be viewed as a Syrian partner against terrorists.
“Syria is ready to cooperate and coordinate on the regional and international level in the war on terror,” Moualem said. “But any effort to combat terrorism should be coordinated with the Syrian government.”
The loss of Tabqa represents a significant setback for Damascus, putting an entire province beyond the government’s reach for the first time since the revolt against Assad turned violent three years ago.
It also exposed the government’s inability to confront the extremists, undermining a pledge by Assad in an inaugural speech marking his new seven-year term in office that the government would soon recapture Raqqah.
“It’s a blow to the regime’s confidence that it can actually prevail,” said Jeff White of the Washington Institute for Near East Policy. “It shows that the regime’s strategy of trying to hang on everywhere in Syria is failing. They just don’t have the resources to do that.”
The Assad government had for months refrained from confronting the Islamic State as the group expanded across northern and eastern Syria, carving out a haven that enabled it to recruit, train and grow ahead of its offensive across the border in Iraq in June.
That changed after the militants’ sweep through Iraq put them within striking distance of Baghdad, prompting airstrikes against Islamic State positions in their Raqqah stronghold.
The militants responded with counteroffensives against the three bases the government had retained in the province. With the fall of Tabqa, all the bases in Raqqah are in extremists’ hands.
The Syrian government said it evacuated most of its troops and aircraft from the base before the defeat. Videos posted on YouTube showed Islamic State fighters celebrating their victory.
The Islamic State also is pressing west and north into portions of Aleppo province that it lost this year to more-moderate rebels, threatening to retake key areas along the Turkish border from which it had been ejected.
On Monday, however, activists in northern Aleppo said rebel fighters had stemmed the advance, pushing the Islamic State out of six villages it had captured in recent days.
Ahmed Ramadan in Beirut and Katie Zezima and Karen DeYoung in Washington contributed to this report.