About 75 U.S. Marines are training with Swedish counterparts to conduct raids and amphibious operations in Sweden’s complicated coastal terrain, which consists of thousands of small islands known as the Stockholm archipelago.

The exercise, dubbed Archipelago Endeavor, is a run up to one of NATO’s largest exercises in more than a decade, known as Trident Juncture, slated to kick off later this fall. The Norway-hosted exercise is expected to include nearly 40,000 NATO forces and dozens of ships.

But views from Moscow see the impending large-scale offensive and defensive NATO maneuvers in the Scandinavian region as a potential header for a war with Russia.

“The troops and equipment of the alliance members and individual partner countries will be used on land, at sea and in the air to improve the skills of defensive and, crucially, offensive operations in the northern latitudes in case of a ‘high intensity’ conflict with a ‘comparable enemy,’” Foreign Ministry spokeswoman Maria Zakharova said in an Aug. 30 briefing.

“This demonstration of military potential will unfold in the immediate proximity to Russian borders and has a clear anti-Russian nature,” she said.

Tensions in the region already are on edge following a decision this summer by Norway to double the U.S Marine rotational training presence to 700. Moscow warned of consequences and even described the move as an attack.

While Sweden is nonaligned country and not a NATO member, the country will be participating in the upcoming Trident Juncture exercise. Archipelago Endeavor affords the U.S. and Sweden to hone various skill sets before the coming large-scale NATO training evolution.

In May, Finland and Sweden both signed onto a letter with the U.S. pledging to build upon a security relationship such as increasing exercises and training.

The push for more formal ties with the U.S. came in reaction to Russia’s 2014 invasion of Ukraine.

Currently, about 75 US Marines and 170 Swedish marines are training in the Stockholm archipelago working on raids and amphibious operations using Sweden’s CB-90 assault craft, according to Marine spokesman Maj. Adrian Rankine-Galloway.

The exercise also allows Marines to get their hands on Sweden’s Carl Gustaf recoilless rifle. The Corps plans to equip its grunts in the coming year with the Gustaf as it phases out the Mk 153 Shoulder-Launched Multipurpose Assault Weapon, also known as the SMAW or SMAW MoD 2.

The three-week training event is scheduled to last to September 8.

“Archipelago Endeavor stands as a prime example of partners working together, and the growth of the mutually-beneficial defense relationship between the U.S. and Sweden,” Rankine-Galloway, said in an emailed statement to Marine Corps Times. “These engagements improve the U.S. military’s ability to support our allies and partners, and rapidly respond in times of threat or crisis.”