*This is a slightly different version of a story we prepared over the weekend for NBC News*

Spring and summer were looking great for European travel, as borders reopened, international restrictions lifted and millions of travelers booked overseas flights, cruises, and tours.

Then Russia invaded Ukraine.

And while it is certainly not the most pressing issue, now, millions of people may be rethinking those summer plans. And a battered travel industry that was anticipating a booming summer season is facing another round of uncertainty.

On Thursday, the Federal Aviation Administration expanded the no-fly zone in eastern Europe for U.S. carriers to include all of Ukraine and Belarus, as well as part of western Russia. Air travel worldwide is getting messier too. After Britain banned Russian Aeroflot flights to the U.K., Russia banned all British flights from its airspace. Since then, other countries have closed their airspace to Russian flights.

Travel advisers say they’ve heard from some travelers who are questioning whether they should keep existing plans or rebook elsewhere. But so far, they say, cancellations aren’t a big problem.

“Given the rapidly changing situation, it’s still too early to tell,” said Erika Richter, spokeswoman for the American Society of Travel Advisors.

Some major travel operators, however, are not waiting to make decisions. They’ve already adjusted certain European itineraries and pulled the plug on other excursions altogether.

 On Thursday, Norwegian Cruise Line, one of the world’s largest cruise operators, said it was rerouting trips around the Baltic region to avoid Russian and Ukrainian ports. Viking Cruises released a statement that said “We have made the difficult decision to cancel all 2022 departures of our Kiev, Black Sea and Bucharest itinerary.” And travel writer and tour operator Rick Steves said in a blog post that his company was canceling tours in Russia for the rest of the year, but Europe would remain on the calendar for now. “It is important to keep geographic realities in mind and remember that a war in Ukraine is as far from our European vacation dreams as a war in Guatemala would be from Texas or Florida,” he said, adding “We see no reason to change the rest of our travel and touring plans.”

The uncertainty created by the Ukraine conflict comes as rapidly falling Covid rates and easing of international restrictions have fueled a strong and steady rise in demand for global travel.

Major U.S. airlines, including American, Delta and United, have more than doubled the number of seats for transatlantic travelers through August, according to CNBC. JetBlue has increased service between New York, Boston and London. International airlines are resuming and expanding service to the U.S. And new carriers, such as Iceland’s low-budget airline Play, have entered the market.

Ticket prices have also increased right along with capacity.

Two months ago, a round-trip ticket to Paris cost around $600, Scott Keyes, founder of Scott’s Cheap Flights, said on Friday. But now, “unless you’re flying from New York City, you’d be lucky to find one for under $750,” he said. “A month from now, $900-plus will be the norm.” And with oil prices rising, Keyes said flights could get even pricier as airlines pass on higher fuel costs to consumers.

But things can change quickly. In the hours after Russia invaded Ukraine, “demand for international travel saw a sharp drop,” Keyes said. He noted that Kayak flight-search data shows international travel searches dropped 8 percentage points overnight as the war began, the steepest fall in months. If that demand stays low “expect to see cheaper fares to Europe, capacity cuts to the number of transatlantic flights or both,” he said.

No matter how much prices bounce around, after two years of being grounded by the pandemic, most travel experts believe pent-up demand will win out.   

 “I have many clients who are traveling to Italy, France, Greece, Croatia, Spain, Portugal, and more,” says Stephanie Goldberg-Glazer of travel company Live Well, Travel Often. “Prices are high, but people are OK with that because they want to travel,” she said.

 Tiffany Scott, of Anchorage, Alaska, feels the same way. She’s waited two years to take a trip to Morocco she booked and partially paid for in 2019. She’s headed there next week and says she’s stopping in France on the way home. “Probably the only thing that would stop me at this point was if Russia was then attacking the other nations in Europe.”

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