The United States accused China and Russia on Monday of shielding North Korea from any action by the U.N. Security Council for its unprecedented spate of intercontinental ballistic missile launches, which violate multiple U.N. resolutions and jeopardize international aviation and maritime safety.

U.S. Ambassador Linda Thomas-Greenfield told a council meeting that Chinese and Russian “obstructionism” was encouraging North Korea “to launch ballistic missiles with impunity” and advance its development of more sophisticated and dangerous weapons.