Swedish Jas 39 Gripens jets escort two U.S. Air Force B-1B Lancers through Swedish airspace as they make their way to Lulea Kallax Air Base, Sweden, June 19, 2023. The bombers landed in Sweden for the first time as part of a rotation in support of U.S. European Command and NATO deterrence initiatives. (Swedish air force)

Two Air Force B-1B Lancers landed in Sweden for the first time, strengthening U.S. ties with the Nordic country and boosting the collective defense of Europe, the service said.

The landings come as Sweden continues its push to join NATO following Russia’s invasion of Ukraine last year and concerns of Russian aggression potentially spreading to other parts of the Continent.

The supersonic strategic bombers, belonging to the 7th Bomb Wing, Dyess Air Force Base, Texas, landed at Lulea Kallax Air Base on Monday, an Air Force statement released the following day said.

The base is in Sweden’s northernmost county near the border with Finland.

The aircraft were participating in an exercise with the Swedish military, Sweden’s Goteborgs-Posten newspaper reported.

Joakim Vidgren, a Lulea Kallax Air Base public affairs specialist, climbs the ladder on a U.S. Air Force B-1B Lancer at the Swedish base, June 20, 2023. Two Lancers landed in Sweden for the first time. (Josiah Brown/U.S. Air Force)

“In these troubled times and in anticipation of Swedish NATO membership, it is important to have strong partners,” Tommy Petersson, the deputy chief of the Swedish air force, told the Gotesborg-Posten.

The bombers’ arrival marks “the next step” in developing collaboration with the alliance, Petersson said.

Following Moscow’s invasion of Ukraine in February 2022, Sweden and Finland applied to join NATO to ensure their security after decades of military nonalignment. Despite their official status, both have a long history of exercises and operations with the Western alliance.

Finland, which shares a more than 800-mile border with Russia, was admitted in April after existing members gave unanimous approval.

But Turkey and Hungary have stalled Sweden’s admission. Turkey says Sweden is providing sanctuary to people linked to the Kurdistan Workers Party, which Turkey considers a terrorist group.

Although Sweden denies harboring terrorists, Turkey has demanded the extradition of dozens of people as a step toward ratifying Swedish membership.

U.S. officials have expressed hope that a unanimous decision to admit Sweden will come next month during a NATO summit in Lithuania.

Senior Airman Marquis Flowers-Robertston, a B-1B Lancer crew chief, talks to a reporter about the aircraft at Lulea Kallax Air Base, Sweden, June 20, 2023. Two Lancers landed in Sweden for the first time. (Josiah Brown/U.S. Air Force)

In the meantime, Sweden continues to cooperate with the bloc.

For more than a week last month, a large swath of the country was used during a Finnish-led air exercise with NATO partners called Arctic Challenge, which included 3,000 service members and 150 aircraft.

The B-1B Lancers, which are four-engine long-range bombers with an intercontinental range, arrived in Sweden as part of separate training.

“The more we can integrate forces and equipment to maneuver across Europe, the more ready we are to face security challenges, now and in the future,” Brig. Gen. Bryony Terrell, the deputy director for strategic plans and policy at U.S. European Command, said in Tuesday’s statement.