Although industry professionals said it was too early to quantify the impact Tuesday's terror attacks would have on tourism to Brussels and other parts of Europe, there was a sense of trepidation in the travel industry that this blow would take longer to recover from than the November attacks in Paris, and could create a chilling effect on visits by vacationers and business travelers that could stretch months into the future.
"This is going to be more protracted," said Kevin Mitchell, chairman of industry advocacy group the Business Travel Coalition, pointing to news reports of breakdowns in communication between European intelligence agencies and failure to recognize the threat posed by the attackers.
"If there are additional plots in the pipeline, and if Europe is in fact overwhelmed, then this could really drag on," he said.
An alert issued the day of the attacks by the U.S. State Department seemed to indicate this possibility, as well. "Terrorist groups continue to plan near-term attacks throughout Europe, targeting sporting events, tourist sites, restaurants, and transportation," it said.
"From a tourism perspective, it's definitely very bad news, having the U.S. travel advisory against all of Europe," said Lynn Minnaert, an assistant professor of tourism at the Tisch Center for Hospitality and Tourism at New York University (and a Belgian native).
"Travel from the U.S. will take a nosedive," she said. "I've never seen an advisory against a whole continent before."
Early samplings of leisure traveler sentiment seemed to bear out Minnaert's prediction. An online poll conducted by Skift.com found that 20 percent of American travelers with plans to visit Europe over the summer months had already canceled their bookings, and another 28 percent were considering doing so.
"We are facing some cancellations coming from groups or individual tourists travelling for leisure purpose," Sophie Ratouis, a spokeswoman for AccorHotels, said via email.
"These cancellations mostly affect hotels in Brussels."
She said Accor was letting guests with bookings in Belgium through April 10 cancel without penalty, or postpone and re-book through September 30.
Business travel might fare somewhat better just because of its less-discretionary nature, but industry observers said this, too, would depend on what the future holds.
"Business travelers are a resilient bunch," said Greeley Koch, executive director of the Association of Corporate Travel Executives. "Unfortunately, this is becoming the new normal in having to deal with these things."
In the near term, Koch added that Americans seemed to be more skittish about traveling to Europe than their Continental counterparts. "In the U.S., we're not used to these things … We'll probably see a falloff in U.S.-based travelers going over there," he said. "I think this one might give people more pause."
"We've had some individuals cancel, but nothing on the group side," said David Peckinpaugh, president of Maritz Travel Company. "So far, I think it's been a very measured response."
What worries tourism professionals, though, is that a contagion could take place and dampen demand for travel not just in Belgium, but across Europe.
In the wake of the Paris attacks in November, the Business Travel Coalition polled its members to gauge their sentiment, and found that respondents were likelier by a degree of five percentage points to suspend travel to all of Europe, rather than just to France, if investigators determined that more attacks were likely.
Reports Thursday of French authorities arresting a suspect in an "advanced stage" of plotting an attack might alarm rather than reassure travelers and corporate travel managers, Mitchell said.
"Even the one foiled yesterday — that still sets off a concern."
Even without further attacks, some, such as NYU's Minnaert, feared that the damage was already done.
"I don't think the country is easily going to recover from this," she said. "Already, people are canceling travel. It's prime time to book travel for summer. It's terrible news."