President Vladimir V. Putin of Russia wrapped up a state visit to one ally, North Korea, and moved on to another, Vietnam, arriving early Thursday hoping to shore up crucial partnerships in the region as he wages a protracted war in Ukraine.

Mr. Putin’s war in Ukraine has left him isolated from the West, and his need for munitions to fight that war has pushed him closer to North Korea and its leader, Kim Jong-un. The two leaders have bonded over their common historical opponent, the United States, and on Wednesday revived a Cold War-era mutual defense pledge between their nations.

In Vietnam, by contrast, Mr. Putin met with officials who have recently forged deeper bonds with Washington. But Moscow has long been Hanoi’s main source of weapons, and Mr. Putin is keen to hold on to that position.

It is Mr. Putin’s fifth visit to Vietnam and follows trips last year by President Biden and President Xi Jinping of China, two leaders who sought assurances from Hanoi that it was not taking the other’s side.

For Vietnam, Mr. Putin’s trip will be an opportunity to solidify ties with Russia, its most important defense partner. Even though it has upgraded relations with the United States, Vietnam was still looking for secret ways last year to purchase Russian military equipment in contravention of American sanctions.

On Thursday morning, in typical scripted fashion, Vietnamese schoolchildren — waving both the Russian and Vietnamese flags — lined the Hanoi streets as Mr. Putin’s motorcade drove by. He was greeted by Vietnam’s newly installed president, To Lam, who gave him a hug.