Russian President Vladimir Putin has accepted an offer from North Korean leader Kim Jong Un to visit Pyongyang at a “convenient time” after the two held summit talks Thursday in Russia’s Far East.

The invitation came as Putin looks to bolster alliances during Russia’s war in Ukraine. Meanwhile, Kim continues advancing North Korea’s military capabilities, reportedly eyeing potential arms deals with Moscow.

The leaders met for over 4 hours, touring space facilities and discussing closer bilateral ties. Kim said he welcomed Putin to visit North Korea to further develop relations, which Putin accepted.

The summit has stoked concerns Kim may try supplying arms to Russia, possibly in exchange for military technology transfers prohibited under UN sanctions on North Korea. Kim’s delegation includes top defense and munitions officials.

Before the talks, North Korea test-fired ballistic missiles in its latest sanctions-breaching launch. The U.S. called any Russia-North Korea military cooperation “troubling.”

South Korea and Japan also warned against violations of U.N. resolutions. But Russia and North Korea appear intent on deepening cooperation between the two isolated states as they contend with international pressure.

With Putin’s acceptance, Kim’s invitation sets the stage for the Russian leader to travel to Pyongyang in a display of solidarity. However, the optics of any arms-related deals risk further backlash for both sanctioned countries.