As the smoke clears from another terrorist strike in the heart of Europe, U.S. lawmakers and security experts are warning violent extremists could similarly detonate bombs in an American airport or subway station.  

Take Dulles International Airport, about 25 miles west of Washington. It is not uncommon on a busy travel day to walk with large pieces of luggage — big enough to carry deadly explosives capable of a Brussels-like strike — from a daily parking garage to the ticketing area without encountering another person.  

The same goes for a seemingly endless list of “soft targets” all over the country. The twin bombings of the Brussels attack , for which the Islamic State claimed responsibility, left at least 31 dead and more than 200 injured, shaking nerves far beyond their target.  

Though Republicans and Democrats in Congress agree the United States is vulnerable, lawmakers and security experts say a fragmented European approach to border security exponentially raises the likelihood of a large-scale terror strike.  

“One thing that happened in Belgium is they have leaky borders, so to speak. They have a lot of people who have been radicalized and recruited and are able to go to Syria and back without being noticed,” said Rep. C.A. Dutch Ruppersberger, D-Md., a former House Intelligence ranking member.  

Images of smoke billowing from Brussels’ Maelbeek metro station and shaky cell phone footage of the carnage inside the Zaventem airport immediately prompted debates over U.S. readiness.  

“It’s the right question to ask,” Perry Cammack, a former Middle East policy adviser to Secretary of State John Kerry, said Tuesday. “I won’t make the prediction that it’s not going to happen here.  

“Someone can be self-motivated and can do a lot of damage without much institutional support,” Cammack said.  

Barry Pavel, a former senior national security adviser to Presidents George W. Bush and Barack Obama, was even more definitive.  

“I’m on record that it will happen here,” said Pavel, now vice president at the Atlantic Council. “I can’t imagine any scenario that would eliminate that threat, even as effective as our homeland security and intelligence capabilities are.”  

The size and scope of those U.S. offensive and defensive security “capabilities” are among the reasons why ISIS operatives or disenfranchised individuals have yet to strike at a U.S. airport, subway system or similar crowded and relatively open location, lawmakers and experts say.  

Another reason: the U.S. has been on war footing since shortly after the 9/11 attacks. “So, structurally we are a lot better off through two administrations than we were 15 years ago,” Cammack said. “And we’re structurally better off and better defended against something like this than the Europeans.  

“They have 20-something countries that have to coordinate, and a problem of various groups not being as integrated in the broader society as they are here,” he added.  

The latter issue is one Ruppersberger said European leaders are going to have to solve — and quickly.  

“An example of that is the guy they arrested who lived in Brussels,” Ruppersberger said, referring to Salah Abdeslam, who authorities say was involved in the November attacks in Paris and was arrested Friday. “It took four months … because he was in a very strong Muslim community where jihadists were protected.”  

Belgium and France, where ISIS claimed responsibility for coordinated attacks in November, have what could be dubbed a “proximity problem,” meaning it is easier for disaffected individuals to slip into Syria or Iraq to link up with ISIS forces.  

“Just look at the raw numbers of foreign fighters returning to various places in Europe,” Pavel said. “And maybe we have a tighter homeland security approach. Certainly it would appear that we do have a more comprehensive law enforcement apparatus domestically.”  

Lawmakers were notably critical of America’s European allies in the hours after the Brussels attacks.  

“To be honest, European security is not to the level that ours is,” said Rep. Peter T. King, R-N.Y., a former Homeland Security Committee chairman. “They’ve been lagging several years behind us. For a number of years, the Europeans thought we were overreacting. The Brits have been very good. But other countries have been playing catch-up.”  

GOP presidential candidates, notably front-runner Donald Trump, on Tuesday called for a variety of stepped-up measures, including waterboarding suspects.  

But Pavel warned “those statements are not productive — in fact, these kinds of statements could make attacks here more likely.”  

Despite the shared concerns, Cammack noted that gun violence and car accidents kill far more Americans each year than terrorist attacks.  

“I worry we’re in this frenzy of a political environment where God forbid we lose a dozen people and we lose our minds collectively,” he said. “We need to guard against that.”  

Contact Bennett at johnbennett@cqrollcall.com. Follow him on Twitter @BennettJohnT.

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