United is adding summer flights to Iceland, Greece and Croatia in the hope that vaccinations will boost travel recovery

United Airlines said Monday it is adding flights to Iceland, Croatia and Greece for the summer in the hope that the relaxed entry requirements will boost demand for popular tourist destinations.

Most of continental Europe remains off limits to most American citizens, and airline executives were pessimistic last week that would change in time for summer vacations.

But United is picking a few European destinations that have already relaxed travel restrictions or are expected to be in the coming weeks.

“It has created a pop in searches,” said Patrick Quayle, United’s vice president of international networks and alliances.

Carrier is adding Chicago-Reykjavik flight from July 1 to October 3 after Iceland announced last month that it would allow tourists from outside of Europe to go without quarantine if they can show evidence of a Covid-19 vaccine .

Following that announcement, Delta Air Lines said it would resume Iceland service from New York City and Minneapolis and add a flight to Boston. United had previously announced a service from Newark to Iceland, which will run from June 3 to October 29.

United will also add service from Newark to Dubrovnik, Croatia, three times a week from July 8 to October 3. That country allows visitors who can show a negative Covid-19 test or proof of vaccination.

Greece said last month it would open its borders in mid-May to vaccinated tourists or those showing a recent negative Covid test result, Reuters reported last week that the shift could happen as early as this week.

United said it plans to add a flight from Washington Dulles to Athens that will operate from July 1 to October 3, in addition to the Newark-Athens service, which is expected to resume in June. 3.

International services are still down, although more people are being vaccinated and some travel restrictions have been lifted.

In May, international flights will account for 40% of United’s total capacity, up from 45% in the same month of 2019. Domestic demand for leisure has recovered to near pre-pandemic levels, executives said recently. American Airlines and Delta say they will deploy large planes – normally used for long-haul international flights – on popular domestic routes this summer.

Internationally, a bright spot for United is northern Latin America, such as Mexico, Central America and the Caribbean, Quayle said. He did not say the rest of Europe will open immediately, although United will resume service from Newark to Milan and Rome and from Chicago to Munich and Amsterdam next month.

“I am most optimistic that the UK and US are creating an airlift between the two countries,” he said.