Airport security is coming under much closer scrutiny after the downing of a Russian passenger flight in Egypt's Sinai Peninsula, and the crash may demonstrate the capability of ISIS to bring down planes with bombs, House Homeland Security Chairman Rep. Michael McCaul said Tuesday.

"They've declared war on Russia," the Texas Republican told Fox News' "America's Newsroom" host Martha MacCallum. "Russia has their own homeland security issues, if you will, to deal with now, and I think this was a retaliation against Russia for their presence in the region."

But if ISIS has indeed moved on to bombs, that adds a "significant departure" from its focus on creating a caliphate, and that could impact the United States as well, McCaul said.

The crash has brought questions about airport security in the United States, noted MacCallum, and McCaul responded that even with the best screening procedures, if there is an "inside job, which seems to be the case here, or if there's corruption or bribery or radicalization from within," that is difficult to stop.

McCaul noted that there have been prosecutions concerning guns and drugs coming to the United States on inbound flights from Puerto Rico, and he has met with key government officials to make sure the last points of departure for planes heading into the United States will have their screening increased.

"There are thousands of airport workers and, no, they don't go through the screening that you and I go through at the airport," said McCaul, noting that he has passed a bill out of his House committee to upgrade standards for vetting airport workers.

"Particularly if you're looking at overseas flights coming in, that's a real high-risk danger," he said. "This is a major game changer with respect to ISIS entering a new chapter."

Related Stories:

• Rep. McCaul: ISIS Likely Brought Down Plane, Russia's 9/11
  
• Investigator: Crashed Russian Jet Not Struck From Outside