It's unclear exactly what new measures are being considered for U.S. airports and U.S. stations in airports overseas. But one source said new measures could include increasing the rates of random screenings at airports, targeting certain types of travelers, or more obvious changes for travelers going through security lines.
The potentially lethal partnership in Syria is at least part of what sparked an advisory to airlines earlier this year to look out for explosives-laden toothpaste tubes, cosmetics and shoes.
Rep. Peter King, a top Republican on the House Homeland Security Committee, said security at airports overseas is "a real concern" to officials in the U.S. and that the federal government needs to be "very aggressive" is responding to it.
"I can’t go into all the details but that is very important to do because a number of airports do not have the type of security that they should have," King said Sunday on ABC News' "This Week," speaking about boosting measures at airports overseas.
Since January, officials with access to the country's most sensitive intelligence have warned publicly that hard-to-detect "technologies and techniques" were being exported to Syria, that foreign fighters from the West were "learn[ing] new things" and "build[ing] new relationships" in Syria, and that "training complexes" were popping up there to prepare Western fighters for terrorist attacks against their home countries.
In May, FBI Director James Comey told a Senate panel the U.S. government has a plan to mitigate the direct threat to the U.S. homeland from Syria, though he declined to offer any details.
More recently, Comey said the U.S. government is spending "a tremendous amount of time and effort trying to identify" anyone who's gone to Syria, but "the challenge" is not missing anyone.
In an exclusive interview on Thursday with ABC News' George Stephanopoulos, President Obama noted that "battle hardened" foreign fighters in Syria are increasingly slipping over porous borders and joining terrorist groups in Iraq, where the group Islamic State of Iraq and Syria -- or ISIS -- is now wreaking havoc.
Though al Qaeda denounced and cut ties with ISIS earlier this year, elements of both groups are committed to attacks against the West.
"Then they come back, they've got European passports ... [and] don't need a visa to get into the United States," the president said of certain foreign fighters.
As part of a much larger request to fund U.S. military operations, the White House has asked Congress to approve $500 million so that U.S. forces can train and arm "moderate" rebels fighting against the Syrian regime.