Baltic leaders reacted warily on Wednesday to reports that Russia could revise the borders of its territorial waters in the region.

Leaders around the Baltic Sea reacted warily on Wednesday to reports that Russia could revise the borders of its territorial waters in the region, with Lithuania’s foreign minister calling it an "obvious escalation” that must be met with an "appropriately firm response.”

In a draft proposal reported by some Russian media, Russia’s Defence Ministry suggests updating the coordinates used to measure the strip of territorial waters off of its mainland coast and that of its islands in the Baltic Sea.

The existing coordinates were approved in 1985, the ministry said, adding they were “based on small-scale nautical navigation maps” and don’t correspond to the “modern geographical situation”.