A challenge is emerging as the U.S. Navy is still determining what its fleet will look like in the future. But in the Atlantic, the U.S. Navy isn’t alone in the undersea fight, according to Adm. Robert Burke, commander of U.S. Naval Forces Europe.

“What I’ll say that we have different in this theater, as opposed to my colleagues in the Indo-Pacific theater, is some extremely high-end capable allies and partners with navies that… operate just like the U.S. Navy and operate with us every day,” Burke said this month at an event hosted by the Center for Strategic and International Studies.

The U.K. and France are “two extremely reliable, extremely capable partners,” Burke said, adding that Canada and Norway “contribute significantly to the theater undersea warfare fight” and that Denmark is “expanding [its] capabilities.”

Most of those countries have “significant” maritime patrol and reconnaissance aircraft, either the U.S.-built P-8 Poseidon, widely regarded as the best sub-hunting aircraft in service, or “a version closely resembling the P-8’s capabilities,” Burke added.