(NewsNation) — An affiliate of the Islamic State Group, or ISIS, has claimed responsibility for the attack that killed more than 100 people in Moscow last week, raising concerns about future possible attacks.

Although Russia might have been an “easier target,” it doesn’t mean the United States won’t be a future target, former CIA and FBI official Phil Mudd said on “CUOMO.”

“If you look at this and accept that America is the head of the snake, they obviously went after Russia because it’s an easier target. But if you think we’re of the hook, that’s nuts. They want to get us.”

Russia suffered the worst terror attack on its soil in decades Friday when assailants descended on a concert hall near Moscow, killing at least 130 people and wounding about 100 more.

Miles Taylor, former Department of Homeland Security chief of staff, agreed that Russia was likely the “path of least resistance,” saying the U.S. is likely the desired target.

“They want to strike the U.S. homeland more than anything,” Taylor said. “The reason they struck Russia and not the United States is because it was an easier target. If ever given the opportunity between one or the other, it would be to strike the United States homeland. That’s more difficult for them.”

It’s a situation that officials have been watching for “quite a while,” he said.

Although there have been reports of U.S. Customs and Border Protection encountering people on the terror watchlist, the nation’s southern border isn’t a primary concern for an attack like this, Mudd said.

“The issue … would be homegrown,” he said. “It’s people who are sympathetic in this country who are already here.”

Taylor agreed, calling threats of terrorists at the border “wildly overstated,” while acknowledging it’s still a concern.  

“It’s obvious to everyone that’s the easy way to get into the United States,” Taylor said. “I do worry, eventually, a terrorist will avail themselves to that pathway.”