What kind of risk does ISIS pose to the U.S.?

In the video of journalist James Foley's execution, ISIS essentially declared war on the United States. But what are the actual risks to the homeland?

Intelligence sources say ISIS, also known as the Islamic State of Iraq and Syria, doesn't appear to present an immediate threat to the homeland. They've demonstrated no operational capability and no real intent to strike America.

But over time, ISIS could emerge as the largest terrorist threat the U.S. faces, CBS News' Homeland Security correspondent Bob Orr reports.

The FBI is tracking more than 100 Americans who have gone to Syria or tried to go to Syria - some to fight with ISIS. At some point, they could come home, and that would be a very big problem.

And as CBS News correspondent Holly Williams reports, ISIS' active recruitment of Westerners, particularly European Muslims, could add to the concern, as those with British and certain other European passports can enter the U.S. without visas.

Right now, ISIS' immediate threat is in Iraq and Syria, where they now hold more territory and is larger than al Qaeda ever was.

CBS News' chief White House correspondent Major Garrett says the White House strategy for dismantling ISIS has these major components:

• Continue U.S. airstrikes in support of Kurdish forces coming from the north and what appear to be newly motivated Iraqi forces hitting ISIS from the south.

• Recruit more military partners. High-level talks are going on now among the United States, Canada, Australia and Britain to join the fight against ISIS.

• Finally, lobby those Sunni-majority countries, specifically Saudi Arabia and the United Arab Emirates, to provide cash and intelligence that the United States and its partners can use against ISIS commanders and its fighters.

Meanwhile, the Pentagon is seriously considering a State Department request to send more security personnel to Baghdad. While ISIS has talked about targeting U.S. diplomatic posts, CBS has been told this is not a response to a direct or immediate threat, State Department correspondent Margaret Brennan reports.

If the request is approved, there would be around 300 troops in addition to the 849 U.S. forces already in Iraq.

The U.S. troops on the ground are not fighting. They're there for intelligence and for advising the Iraqi forces.