Will US get drawn into Syrian war?
At the heart of US President Barack Obama's quandary over the Islamic State militants is their haven in Syria.
The president may continue helping Iraqi forces try to reverse the group's land grabs in northern Iraq by providing more arms and American military advisers and by using US warplanes to support Iraqi ground operations.
But what if the militants pull back, even partially, into Syria and regroup, as Defense Secretary Chuck Hagel on Thursday predicted they would, followed by a renewed offensive?
''In a sense, you're just sort of back to where you were'' before they swept into Iraq, said Robert Ford, a former US ambassador to Syria who quit in February in disillusionment over Obama's unwillingness to arm moderate Syrian rebels.
''I don't see how you can contain the Islamic State over the medium term if you don't address their base of operations in Syria,'' he said in an interview before an intensified round of US airstrikes this week helped Kurdish and Iraqi forces recapture a Tigris River dam near Mosul that had fallen under Islamic State control.
On the other hand, Obama has been leery of getting drawn into the Syrian civil war, which began in 2011.
More immediately perhaps, Obama faces choices in Iraq, whose sectarian divisions and political dysfunction created the opening that allowed Islamic State fighters to sweep across northern Iraq in June almost unopposed. They captured US-supplied weapons that Iraqi forces left behind when they fled without a fight.
Among his options:
-Sending more troops to Baghdad to strengthen security for the US Embassy, as requested by the State Department. Officials said the number under consideration is fewer than 300. They would be in addition to the several hundred US troops already in the capital to help protect US facilities and personnel.
-Speeding up the arming of Iraqi and Kurdish forces. The administration has been supplying Iraqi government forces with Hellfire missiles, small arms and ammunition, but critics say the pace has been too slow. The administration has been reluctant to openly arm the Kurds, since their militia, known as the peshmerga, is a semi-autonomous force seen in Baghdad as a threat to central government authority.
-Increasing the number and expanding the role of the dozens of US military advisers who are in Baghdad and the Kurdish capital of Irbil to coordinate with Iraqi forces. They could be given more direct roles in assisting the Iraqis on the ground by embedding with Iraqi or Kurdish units in the field or scouting targets for US airstrikes.
-Committing US ground troops in Iraq. Obama has said repeatedly he would not do this. ''We're not the Iraqi military. We're not even the Iraqi air force,'' Obama said on Monday. ''I am the commander in chief of the United States armed forces, and Iraq is going to have to ultimately provide for its own security.''
-Extending the Iraq air campaign to Islamic State targets in Syria. Stretches of eastern Syria are a sanctuary for the group, also known by the acronyms ISIL or ISIS. The US has warplanes available in the Middle East and Europe that could vastly increase the number and intensity of strikes in eastern Syria if Obama chose.
Defense Secretary Chuck Hagel, at a Pentagon news conference on Thursday, said that "we are looking at all options" to stop the expansion of an organisation he said was as "sophisticated and well-funded as any group that we have seen".
"They're beyond just a terrorist group," Hagel said. "They marry ideology, a sophistication of strategic and tactical military prowess. They are tremendously well-funded."
Asked whether airstrikes against the group in Syria were under consideration, Hagel said that "we continue to explore all options . . . and how best we can assist partners in that area, the Middle East, particularly in Iraq".
"We will continue to stay focused . . . on what we're doing now and exploring all options as we go forward," Hagel said.
A senior defence official, speaking on the condition of anonymity after the news conference, said that no decision has been made to expand airstrikes into Syria, and the White House has not requested new military options.
US airstrikes in Iraq began on August 8, as militants there continued their bloody sweep across the country and closed in on the Kurdish capital of Irbil, where the United States has military facilities and a consulate. US military officials said on Thursday that the US military has carried out a total of 90 strikes, 57 of them in the vicinity of the Mosul Dam. This week, Obama announced that Iraqi and Kurdish forces had retaken the dam, near Iraq's northern border with Turkey, from Islamic State control.
After Foley's death this week, Obama called the Islamic State a "cancer," and Secretary of State John Kerry said the group must "be crushed."
General Martin Dempsey, chairman of the Joints Chiefs of Staff, was more measured in his remarks with Hagel on Thursday, saying it is possible for the United States to contain the group. But he said the Islamic State threat must be addressed in both Iraq and Syria.
"This is an organisation that has an apocalyptic, end-of-days strategic vision and which will eventually have to be defeated," Dempsey said. "To your question, can they be defeated without addressing that part of their organisation which resides in Syria? The answer is no. That will have to be addressed on both sides of what is essentially at this point a nonexistent border."
Dempsey said one immediate concern about the deterioration in Iraq and Syria and the rise of the Islamic State is the number of Europeans and other foreigners who have travelled to the region to join the militant movement.
"Those folks can go home at some point," Dempsey said. "It's why I have conversations with my European colleagues about their southern flank of NATO, which I think is actually more threatened in the near term than we are. Nevertheless, because of open borders and immigration issues, it's . . . an immediate threat."
-AP/The Washington Post