United Airlines is working to get ahead of what it expects to be a strong demand for transatlantic flights to Europe this summer. In preparation, United is adding 30 new and renewed flights to overseas cities as part of its largest expansion in decades.

On Tuesday, United announced that it would be increasing its flights from cities like New York, Washington, Chicago, and Boston to European and Middle Eastern destinations.

A number of the renewed flights are to popular business and tourist hubs like London, but the airline is also opening five new routes to Palma de Mallorca, Spain; Bergen, Norway; Amman, Jordan; Portugal’s Azores Islands and the Canary Islands as part of its expansion.

United’s expansion has exceeded the reach it had prior to the start of the COVID-19 pandemic. According to the airline, the additional destinations and renewed routes represent a 25% expansion from 2019.

"We have long anticipated a strong demand recovery, evidenced by our large, strategic expansion in Europe, and with these new flights, we're proud to offer our customers more options and access than ever before," said Patrick Quayle, senior vice president of international network and alliances at United.

United’s optimism follows a general ease of international anxiety about the Omicron variant of COVID-19 that sparked anxiety at the start of the year for its contagiousness. While concern still remains about the so-called “stealth variant”, travel restrictions on both sides of the Atlantic have continued to ease, incentivizing more potential travelers.

Since the start of the COVID-19 pandemic, flights have been struggling to recover to pre-pandemic levels. According to the Transportation Security Administration, there were 2,182,717 passengers traveling through airports as of April 25. The number was significantly higher than the amount seen at the same time last year, but still below levels seen in 2019 before the pandemic disrupted air travel.

But despite the relaxing of restrictions, airlines are still concerned about how mandatory testing at airports is holding back demand. Their concern is that Americans interested in international travel are concerned that they may test positive for COVID-19 before or during their trip, creating secondary thoughts that hold them back from booking tickets.

"The testing requirement is preventing a lot of people from taking trips that they might otherwise have taken," Scott Keyes, a flight expert and founder of Scott's Cheap Flights, told CBS News last month.