The U.S. is mulling European visa restrictions due to terrorism fears.

EU Visa waiver
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European nationals traveling to the U.S. may soon face more obstacles in entering the country, as leadership from the U.S. administration called the visa waiver program into question.

U.S. Department of Homeland Security director John Kelly said Wednesday the U.S. needs to reexamine its agreement with Europe that waives visas for visits less than 90 days, saying Europeans posed a potential terror risk.

"We have to start looking very hard at that [visa waiver] program," he said during an appearance at George Washington University in Washington, D.C, CNN Money reported. "Not eliminating it and not doing anything excessive but look very hard at that program."

"We are the Super Bowl in terms of terrorists," Kelly said. "That's where they wanna come."

First established in 1986, the visa waiver program has allowed people from 38 countries, including some of the U.S.’ closest allies, to visit the country for brief stays without needing to apply for a visa. Residents of these countries must still pass through the Electronic System for Travel Authorization (ESTA) online, through which the U.S. government can assess risk.

Thousands of European nationals have traveled to Iraq and Syria to join militant organizations such as the Islamic State group, also known as ISIS. In the November 2015 terror attacks in Paris that saw 129 fatalities, all of the attackers were European passport-holders, several of whom had traveled to train with ISIS before returning to France or Belgium.

The visa waiver program is not a free pass into the country, however. Dual-nationals or people who have traveled to Iraq, Iran, Syria, and Sudan since 2011 do not qualify. Former president Barack Obama instituted these rules to increase regulation of the program after the Paris attacks.

While the threat of terrorism is a concern, U.S. leadership needs to balance the risk potential with the ways in which limits on the visa waiver program could jeopardize diplomatic relations, according to a security expert.

“It’s clearly a concern,” Thomas Sanderson, a terrorism analyst at the Center for Strategic and International Studies, told Travel + Leisure, adding, “The airlines are still very much a point of entry.”

The hassle of getting a visa might not be the only thing to deter Europeans from going through a more restrictive vetting process, according to Sanderson.

“It’s not just the process, it’s the personal insult they would feel,” he said. “It requires thinking and review but not elimination. It’s too important.”

Millions of Europeans and other travelers on the visa waiver program visit the U.S. each year, and the money they spend on hotels, flights, restaurants, and other attractions contributes greatly to the economy.

Credit: Chris Tobin/Getty Images

Visa waiver program participants spent $84 billion on goods and services in 2014 and boosted local economies by nearly $231 million per day, according to the Department of Commerce. Any limits on the program could mean significant losses for tourism revenue.

“I hate to use the word, but it would be devastating,” Chris Heywood, SVP of global communications for NYC & Company, the official New York City tourism board, told T+L.

New York City is the top destination for international travelers in the U.S., and on average they spend four times as much money as domestic tourists to the city do, Heywood noted. In 2015 alone, British tourists spent $1.6 billion on goods and services in the city, French visitors spent $1.11 billion, and Germans spent $1.1 billion.

“So many destinations are fighting for the same tourism dollar, so people will gravitate to places that are more welcoming,” Heywood said.