Nobody expects ISIS to go quietly into the night. That's not what Islamist terrorist groups do.

What this particular group wants now is revenge for their humiliating defeat in Syria and Iraq. The question is: Where will they strike to try to save face? America is on watch to make sure it doesn't happen here.

Make no mistake about it, losing its self-proclaimed caliphate was a devastating blow to ISIS, psychologically as well as militarily.

In the Middle East, power is honor. By controlling a vast territory with over 10 million inhabitants, ISIS commanded honor and attracted more followers eager to back this "strong horse."

But that once strong horse is now seen as powerless in the wake of a counteroffensive that eliminated its control of every last village. Nothing could be more degrading.

The only way to get back in the game and regain their "honor" is to demonstrate they can continue to kill innocents and the bigger the numbers the better.

There is no question that America tops the list of places where ISIS would most like to stage a horrific attack. But the question is: Can they?

Recent media accounts of documents uncovered in the Middle East talk of active operational planning for major terrorist attacks in Europe, similar to the 2015 strike in Paris, France, that left 89 dead. From the reporting, however, it is not clear how much this planning is aspirational and how much reflects actual capability.

That said, it is clear why ISIS might target Europe instead of the U.S.

For one thing, they have done it before and had success. The waves of Middle Eastern migration have been exploited to put in place a network of operatives and sympathizers stretching from the UK over half of Western Europe.

In addition, European police forces are struggling to keep up with the threat. They lack officers with language skills and training in community policing and intelligence-led policing, the tools most useful in rooting out local violent extremist activity.

In contrast, the U.S. is a much harder target. The FBI has made countering transnational Islamist terrorism Job #1. Combating terrorism is a principle duty of the Department of Homeland Security, as well. State and local law enforcement also continue to dedicate significant resources to the mission.

It is not like the terrorists aren't trying. My colleagues at The Heritage Foundation maintain a database of all the Islamist-related terror plots laid against U.S. territory since 9/11, 2001. It currently documents 109 known plots, including two this month.

What is most significant is that the overwhelming number of these plots are thwarted often by local law enforcement before anyone gets hurt.

All the recent plots against the U.S. lack the sophistication and scale of the 9/11 attacks. Transnational terrorist groups have been degraded to the point that they now appear to lack the capacity to pull off anything on that scale.

But we can never say never. Groups like ISIS have demonstrated both resilience and innovation. While they are most likely to be content with targeting Europe and the Greater Middle East including North Africa for now, no one knows when they will come after the red, white, and blue.

Which is why America must always be ready. Readiness includes not just continuing vigilant counter-terrorism operations here at home, but also taking the fight to ISIS and al Qaeda overseas.

They can't be allowed to have sanctuaries. They can't be allowed to rebuild their infrastructure, networks and financing. They can't be allowed to partner-up with transnational criminal networks and state actors.

Americans should never get complacent about the terrorist threat. But as long as we keep heavy pressure on the transnational groups, we can sleep better than most.