The United Nations member states upholding the Korean War armistice, according to U.S. Defense Secretary Lloyd Austin, expressed worry on Tuesday that China and Russia were assisting North Korea in enhancing its military capabilities by allowing Pyongyang to avoid UN sanctions.

In a statement made during the Seoul meeting that was attended by Austin and defense officials from the 17 nations that comprise the U.N. Command (UNC), the organization in charge of overseeing the armistice, the UN states and South Korea pledged a coordinated reaction to any aggression or attacks by North Korea on the south.

“We are deeply concerned that the PRC and Russia are helping the DPRK expand its capabilities by enabling it to evade sanctions from the U.N. Security council,” Austin said, referring to the People’s Republic of China and North Korea’s official name, the Democratic People’s Republic of Korea.

“We’re also troubled by the recent growth in military cooperation between Russia and the DPRK,” he said.

Washington has accused North Korea of supplying military equipment to Russia for use in its war with Ukraine, and Moscow of providing technical military support to help the North.

North Korea and Russia have denied any arms deals, though their leaders pledged closer military cooperation when they met in September in Russia’s far east.

Asked about Austin’s comment, Kremlin spokesman Dmitry Peskov said: “All such statements are absolutely unfounded, they are not substantiated by anything, and each new similar statement only further devalues all others in this regard.”

China, North Korea’s closest ally, has said it was complying with international obligations.

The UNC “will be united upon any renewal of hostilities or armed attack on the Korean peninsula,” a joint statement between UNC and South Korea said, condemning North Korea’s “unlawful” nuclear and ballistic missile programs.

South Korean Defence Minister Shin Won-sik said Pyongyang had been warned not to attempt any aggressive acts, noting that unlike in 1950, when the Korean War broke out, North Korea is now a member state of the United Nations.

NORTH CALLS FOR UNC TO BE DISSOLVED

“If North Korea ever invades the South again, it will be self-contradictory, where a U.N. member state would be attacking the U.N. Command,” Shin told the meeting. “If the countries that backed North Korea during the Korean War ever try to help again, then those countries will also receive grave punishment from the international community along with North Korea.”

China and the Soviet Union backed the North in combat against U.N. member states led by the United States. China and North Korea are parties to the armistice with the UNC.

The UNC member states, which include the United States, Britain, Australia and Turkey, sent troops or contributed medical support during the 1950-53 Korean War.

Established in 1950, the UNC was mandated to restore peace and enforce the armistice while acting as a channel of communication with North Korea.

It is led by the commander of the U.S. military stationed in South Korea.

North Korea on Monday called the UNC “a U.S. tool for confrontation” that has nothing to do with the United Nations and an “illegal war organisation” that must be dissolved if the outbreak of a new war on the Korean peninsula is to be prevented.

On Monday, Austin and Shin agreed to revise a bilateral security agreement aimed at deterring North Korea’s growing nuclear and missile threats.

The defence chiefs said they would step up joint drills and cooperate with Japan to deter and better prepare for any North Korean attack, while seeing the need for dialogue as a path toward peace on the peninsula.

The U.S. and South Korean navies are carrying out joint drills this week off the east coast of the peninsula, including anti-submarine exercises, the South Korean navy said on Tuesday.