Russian President Vladimir Putin ended a state visit to ally North Korea to visit another ally, Vietnam, arriving early Thursday morning local time as he seeks to strengthen ties with a key partner in the region during the protracted war in Ukraine.

Putin’s war in Ukraine has isolated him from the West, and his need for munitions has brought him closer to North Korea and its leader, Kim Jong Un. The two leaders, who have deep ties over their shared historical adversary, the United States, met on Wednesday.Restored the two countries’ Cold War-era mutual defense commitment.

Putin has arrived in Hanoi, according to Russian state media. In Vietnam, by contrast, he will meet officials who have recently forged closer ties with Washington. But Moscow has long been Vietnam’s main source of arms, a position Putin wants to maintain.

This is Putin’s fifth visit to Vietnam. Last year,US President Bidenand Chinese President Xi Jinping have both visited Vietnam, with both leaders seeking assurances from Hanoi that they would not side with the other.

For Vietnam, Putin’s visit will be an opportunity to consolidate ties with Russia, Vietnam’s most important defense partner. Although Vietnam upgraded its ties with the United States, it was still looking forSecret PathPurchase of Russian military equipment, which violates U.S. sanctions.

Washington accused Hanoi of inviting the Russian leader, saying “no country should give Putin a platform to promote his war of aggression, which would allow him to normalize his atrocities.”

This week,Vietnam’s new presidentTo Lin told the Russian ambassador to Vietnam that Hanoi “has always considered Russia as one of the priority partners in Vietnam’s foreign policy.”

Here’s what you need to know about relations between Moscow and Hanoi.

The Soviet Union was one of the first countries to diplomatically recognize the then Democratic Republic of Vietnam, or North Vietnam, in 1950. For decades, Moscow became Vietnam’s largest aid donor, providing military assistance as Hanoi fought France and the United States.

Defense ties underpin many of the ties between the two countries, which share a common communist ideology, and Putin’s arrival in Vietnam with new Defense Minister Andrei Belousov underscored the centrality of security to his visit.

Nguyen The Phuong, who studies Vietnam’s military at the University of New South Wales in Australia, said Russian equipment accounts for 60% to 70% of Vietnam’s defense arsenal. Russia has provided Vietnam with coastal defense missile systems, six Kilo-class submarines, fighter jets and a host of lethal weapons.

Nguyen said almost all of Vietnam’s naval vessels are from Russia. He also said that Russia’s T-90 tanks, the last Russian weapons Vietnam purchased in 2016, form the backbone of Vietnam’s armored forces. This means Vietnam will still rely on Russia in the coming years.

But Western sanctions on Moscow have left Hanoi worried about whether Russia remains a reliable supplier and made it increasingly awkward for Vietnam to continue dealing with Russia while engaging with the West.

Many Vietnamese leaders are also well aware of the plight of Russian troops in Ukraine — videos have shown T-90 tanks being blown up by drones used by Ukraine — and are aware of Russia’s deepening ties with China, which they see as a threat because of their long-standing territorial dispute with Vietnam in the South China Sea.

In recent months, Vietnam has turned to countries such as South Korea, Japan and the Czech Republic as alternative sources of weapons. It is also trying to build up its own defense industry. It hopes India, another former Soviet ally, can adapt some of its weapons.

The United States has been actively trying to provide Vietnam with more weapons, and senior U.S. officials have visited Vietnam in recent months. But analysts say Vietnam’s defense top brass remains skeptical of Washington. They are reluctant to tie their fate to a country whose arms sales must be approved by Congress, which could make human rights a condition of the deal.

Russia has a large stake in Vietnam’s lucrative oil and gas industry. Viet Somnath, a joint venture between Russia’s Zarubezhneft and Vietnam’s state-run Oil and Gas Group, operates Vietnam’s largest oil field, Bach Ho.

VietSooil’s profits have brought millions of dollars to Russia and Vietnam. Zarubezhneft and another Russian state energy company, Gazprom, are also involved in oil exploration projects in Vietnam.

For Moscow, the projects come at a time when Russian oil and gas exports to Europe are being squeezed following EU sanctions.dramatically dropBut the projects have angered Beijing because they are located in waters that China claims as part of its territory.

Vietnam was also popular with Russian tourists before the coronavirus pandemic. In 2019, Russia sent the sixth-highest number of tourists to Vietnam among all countries, second only to the United States. But the number fell during the pandemic, and the number of tourists fell further in 2022 when Vietnam stopped direct flights between the two countries after Russia invaded Ukraine. Direct flights resumed this year.

Since the 1950s, thousands ofVietnamese Communist Party officialbusiness executives, doctors, teachers and soldiers were trained in the Soviet Union and Russia. Among them is Nguyen Phu Trong, the current General Secretary of the Communist Party of Vietnam.

But some argue that the Soviet Union’s last leader, Mikhail Gorbachev, and Russia’s first president, Boris Yeltsin, overlooked that deep relationship.

“The Vietnamese felt that Gorbachev abandoned Vietnam in the 1980s to improve relations with China, and that Yeltsin paid little attention to Vietnam throughout the 1990s,” said Ian Storey, a senior fellow at the Yusof Ishak Institute of Southeast Asian Studies in Singapore. “When Putin came to power in 2000, he gave Vietnam a lot of face. So the Vietnamese are grateful for that.”

He also said that Vietnamese leaders like Putin because “he has put Vietnam-Russia relations back on track.”