Putin Abandons Caution on North Korea in Pursuit of Victory in Ukraine

Thousands of North Korean men converged on Russia’s Pacific Coast six years ago. President Vladimir V. Putin had decided to punish North Korea for developing nuclear weapons, and the men — North Korean laborers used by Russian businesses — were being sent home.

The North Koreans are now being welcomed back to the same Russian region, this time as soldiers. American, Ukrainian and South Korean intelligence agencies have said thousands of them have arrived in recent weeks to aid the Russian war effort in Ukraine, deepening a military alliance resurrected by Mr. Putin and the North Korean leader, Kim Jong-un, earlier this year.

The arrival of North Korean soldiers highlights the dramatic transformation of Russia’s relationship with its neighbors and the wider world following the invasion of Ukraine more than two years ago.

Russia’s complex economic and political interests on the global stage have been subsumed by the narrow calculus of the war, which the Kremlin has portrayed as an existential struggle for national survival.

Mr. Putin’s sudden embrace of North Korea, a pariah to much of the world, also shows how the war in Ukraine has erased the last areas of Russia’s cooperation with the West, throwing issues of global importance such as arms control and nuclear nonproliferation into dangerous, uncertain territory. The days when Russia cooperated with a broad coalition, including China and the United States, to try to rein in the North’s nuclear ambitions have vanished.

“This is a major about face for the Russian policy,” said Alexander Gabuev, an expert on Russia’s relations with Asia at the Carnegie Russia Eurasia Center, a Berlin-based research group.