WASHINGTON (AP) — Russia is shipping refined petroleum to North Korea at levels that exceed U.N. Security Council limits, the White House said Thursday, signaling it will impose new sanctions against those involved in facilitating the transfers.

The United Nations had set an annual 500,000 barrel global cap on refined petroleum products to North Korea as part of its yearslong effort to curb Pyongyang’s nuclear weapons program.

White House national security spokesman John Kirby said that in March alone, Russia shipped more than 165,000 barrels of refined petroleum to North Korea. With the close proximity of Russian and North Korean commercial ports, Russia could sustain these shipments indefinitely, he said.

The disclosure came the day after a U.N. panel of experts monitoring enforcement of sanctions against North Korea for its nuclear weapons and missile programs was disbanded. Russia, one of five permanent members of the Security Council, had blocked the panel’s renewal.