(UPDATE) SEOUL — North Korea's foreign minister said a new multilateral sanctions monitoring team led by the United States was "utterly unlawful and illegitimate," state media reported on Sunday.

The United States, South Korea and Japan on Wednesday announced the launch of a new multinational team to monitor the enforcement of sanctions against North Korea after Russia and China thwarted monitoring activities at the United Nations.

The team was introduced after Russia in March rejected the annual renewal of a UN panel of experts that had over the past 15 years overseen the implementation of sanctions aimed at curbing North Korea's nuclear and missile programs.

China, North Korea's chief ally and economic lifeline, abstained from the vote.

Tensions on the Korean peninsula have intensified in recent years with North Korea stepping up its development of a series of ballistic missiles and a nuclear arsenal, drawing international sanctions, and forming close military relations with Russia.

Washington has been strengthening its security cooperation with key regional allies South Korea and Japan.

"The forces involved in the smear campaign against the DPRK will have to pay a dear price for it," Foreign Minister Choe Son Hui said via state news agency KCNA, using the country's official name.

Choe criticized the team, which would be joined by eight other countries, as Washington's misconduct of flouting the international order and as "the most undisguised violation" of North Korea's sovereignty.

Washington and Seoul have warned of North Korea's close military ties with Moscow.

South Korea's spy agency said on Friday that North Korea has sent 1,500 special forces troops to Russia's Far East for training and acclimatization at local military bases and will likely be deployed for combat in the war in Ukraine.

Russia and North Korea both deny they have engaged in arms transfers.

The Kremlin has also dismissed South Korean assertions that North Korea may have sent some military personnel to help Russia against Ukraine.

US Defense Secretary Lloyd Austin said he could not confirm reports that North Korea has sent troops to Russia ahead of what could be a deployment to Ukraine, but added that such a move would be concerning, if true.

Meanwhile, Chinese President Xi Jinping said he was willing to lead friendship and cooperation with North Korea to "sustainable and stable development" and contribute to "safeguarding regional and global peace," North Korean state media reported on Sunday.

Xi sent a reply to North Korean leader Kim Jong Un congratulating China's founding anniversary, according to KCNA.