.SEOUL, South Korea (AP) – North Korea expressed rare gratitude Thursday for U.S. help in ending a high-seas standoff with Somali pirates, a sign of warming ties between the longtime foes fostered by progress on Pyongyang’s nuclear disarmament.

The U.S. Navy’s aid to North Korean sailors last week was unprecedented in the half century of hostility between the Cold War enemies, according to the Naval Historical Center in Washington.

The North Korean Central News Agency hailed the maritime collaboration as a “symbol of cooperation” between the two countries “in the struggle against terrorism.”

“The pirates’ recent armed attack on our trading ship was a grave terrorist act perpetrated against a peaceful ship,” KCNA said. “We feel grateful to the United States for its assistance given to our crewmen.”

The last notable maritime encounter between the two countries was in 1968, when the North seized the USS Pueblo while it was on an intelligence-gathering mission off the North Korean coast and held 82 Americans as prisoners of war for 11 months.

The USS Pueblo is the only active-duty U.S. warship in the hands of a foreign power and remains on display as a tourist attraction in Pyongyang.