The US has accused North Korea of providing Russia with ballistic missiles and launchers for its war with Ukraine.
National security spokesperson John Kirby told reporters the United States will raise the development with the United Nations Security Council.
He said North Korea's arms transfer to Russia was a "significant and concerning escalation" and said the United States would impose additional sanctions against those facilitating the arms deals.
He added that Russian forces fired at least one of the Korean missiles into Ukraine on December 30 with more fired in an overnight aerial attack on Tuesday.
Kirby said Iran has not delivered close-range ballistic missiles to Russia but Washington believes Russia intends to purchase missile systems from Iran.
Moscow has been heavily reliant on Iran for drones and other weaponry for use against Ukraine.
The UK condemned Russia’s decision to use ballistic missiles sourced from North Korea.
The Foreign Office said the attacks are a sign of Russia’s “desperation” and a violation of UN Security Council Resolutions.
A Foreign, Commonwealth and Development Office spokesperson said: “The UK strongly condemns Russia’s decision to use ballistic missiles sourced from North Korea in recent attacks against Ukraine. We urge North Korea to cease its arms supply to Russia.
“Russia is turning to North Korea for its weapons in pursuit of its cynical and ill-conceived military aims in Ukraine. This is symptomatic of its isolation on the world stage and a sign of its desperation.
“Furthermore, this activity is in violation of multiple UN Security Council Resolutions – which Russia supported as a permanent member.
“Any support for North Korea’s own illegal weapons programmes risks significantly undermining the UN’s long standing commitment to security, and further destabilising the region.
“North Korea is subject to a robust sanctions regime, and we will continue to work with our partners to ensure that North Korea pays a high price for supporting Russia’s illegal war in Ukraine.”
It comes as South Korea's intelligence service said the young daughter of North Korean leader Kim Jong Un is seen as his likely heir apparent to power in the isolated and secretive dictatorship.
There has been intense outside debate and speculation about the girl, who is reportedly about 10 years old and named Ju Ae, since she made her first public appearance in November 2022 when she watched a long-range missile test launch with her father.
The girl has since accompanied her father to several major public events, with state media calling her Kim Jong Un's "most beloved" or "respected" child and churning out footage and photos proving her rising political standing and closeness with her father.Since its foundation in 1948, North Korea has been successively ruled by male members of the Kim family. Kim Jong Un inherited power upon his father Kim Jong Il's death in late 2011. Kim Jong Il took over power after his father and state founder Kim Il Sung died in 1994.
