Russia’s foreign minister on Saturday cautioned the United States, South Korea and Japan against forming a security alliance aimed at North Korea while he was on a visit to strengthen military and other ties with one of Russia’s closest allies.

Foreign Minister Sergey Lavrov travelled to the eastern city of Wonsan in North Korea on Friday to meet his North Korean counterpart Choe Son Hui.

Russia and North Korea have seen their relationship grow rapidly in recent years as North Korea has sent troops and ammunition to support Russia’s war in Ukraine in exchange for military and economic help which has raised concerns in the United States and South Korea about Russia possibly giving North Korea sensitive technologies that could further develop its nuclear and missile capabilities.

After his meeting with Choe on Saturday, Lavrov accused the United States, South Korea and Japan of increasing their military presence near North Korea.

“We warn against exploiting these ties to build alliances directed against anyone, including North Korea and, of course, Russia,” he told reporters as quoted by Russia’s state-run Tass news agency.

In response to North Korea’s growing nuclear threat, the United States, South Korea and Japan have been stepping up their joint military drills or resuming previous ones.

On Friday, the three countries carried out a joint air drill near the Korean Peninsula involving American bombers that can carry nuclear weapons while their top military officials met in Seoul and called on North Korea to stop all illegal actions that threaten peace in the region.

North Korea sees these large US-led drills as practice runs for an invasion and has repeatedly said that it must build nuclear weapons to protect itself from what it calls American military threats.

Lavrov said that Russia understands why North Korea decided to pursue nuclear weapons.

“The technologies used by North Korea are the result of the work of its own scientists. We respect North Korea’s aspirations and understand the reasons why it is pursuing nuclear development,” Lavrov said.

During their meeting, Choe reaffirmed that North Korea “unconditionally” supports Russia in its war against Ukraine and she called the relationship between the two countries “the invincible alliance.”

Lavrov added that he had once again thanked North Korea for the role its troops played in resisting a Ukrainian attack on the Kursk region near Russia’s border.

The meeting was held in Wonsan, which is also the site of a large beach resort recently opened by North Korea that it claims can host around 20,000 visitors.

Lavrov said at the start of the meeting, “I am sure that Russian tourists will be increasingly eager to come here. We will do everything we can to facilitate this, creating conditions for this, including air travel,” according to the Russian Foreign Ministry.

The Wonsan-Kalma coastal area is part of North Korean leader Kim Jong Un’s plan to use tourism to help fix the country's struggling economy, though the future of this resort remains uncertain since the country has not reopened its borders or welcomed Western visitors in full.