South Korea is closely monitoring developments in the latest military exchanges between North Korea and Russia and will consider measures in response, a senior official at the Foreign Ministry in Seoul said Saturday.

“Any weapons exchanges between the two are a clear violation of United Nations Security Council resolutions and a threat to peace and stability in the Korean Peninsula,” the ministry official said, referring to sanctions the North has been facing.

“We’re also closely paying attention to the latest announcement from the US,” the official added, referring to comments Friday by US National Security Council spokesperson John Kirby.

The US said Pyongyang had delivered weapons to Russia for its war in Ukraine. Kirby told reporters that the Kim Jong-un regime provided 1,000 containers of military supplies. The details of what those munitions included were not disclosed.

“We condemn the DPRK for providing Russia with this military equipment, which will be used to attack Ukrainian cities, kill Ukrainian civilians and further Russia’s illegitimate war,” Kirby said, referring to the North’s official name, the Democratic People’s Republic of Korea. The US believes the Kim regime in return would receive weapons technologies, like those used to advance missiles.

Closer ties between Kim and Russian President Vladimir Putin were forged last month when they met in far eastern Russia. The first summit in four years underscored the growing global isolation they face as Moscow seeks to replenish its depleted stores of weapons with Pyongyang’s help. The isolated country has a vast supply of Soviet-era weaponry that Russia can easily deploy. Seoul and Washington have warned of a price to pay should such transfers take place.

Citing previous efforts to sanction those facilitating arms deals, Kirby noted the US would pursue new sanctions to curb additional activity, in line with the South Korea’s pledge to do the same. South Korea President Yoon Suk Yeol last month called for a tighter international front on the issue, saying North Korea-Russia military cooperation is “not only illegal, but unjust.”

Kirby added that the US has already “observed Russian ships offloading containers in the DPRK.”

According to the White House account, about 300 shipping containers were picked up at North Korea’s Najin port from Sept. 7-8. The shipment was transported to Dunay in Russia’s Far East by the Russian-flagged vessel M/V Angara on Sept. 12 -- the day before the Putin-Kim summit.

Those containers from the North were then moved by rail to the ammunition depot in southwestern Russia near Tikhoretsk, about 290 kilometers from the Ukrainian border on Oct. 1.