The Arctic Edge exercise involved 1,500 troops and was an early test of the command's new special operations component.
The U.S. Navy has begun five weeks of submarine training and testing off Alaska's north coast.
Commandant Adm. Paul Zukunft said the service now has the backing of Congress and the White House.
The disappearance of the ice pack has made Arctic passages potentially viable alternatives to existing routes.
After 11 years and some big changes, the Coast Guard is diving in the Arctic again, with an assist from the Navy.
Russia now has two bases in the Arctic: Trefoil and Nagorskoye.
The U.S. Naval War College has opened a new institute to zero in on Russia's approach to maritime issues.
Officials spent two days practicing how they would respond if a large-scale emergency were to happen in the Arctic.