WASHINGTON — North Korea has punched a hole in the web of United Nations sanctions intended to pressure Pyongyang to give up its nuclear-weapons programs and long-range missiles, accelerating its import of petroleum products through illicit ship-to-ship transfers and stepping up coal exports, according to a report to the U.N. Security Council by a panel of international experts that is expected to be issued this week.

Pyongyang has also defied sanctions by selling small arms and other military equipment to the Iran-backed Houthi rebels in Yemen and to Libya and Sudan. They made the arms shipments through foreign intermediaries, including a Syrian arms trafficker in the case of the Houthis.

The report is a comprehensive assessment that is generally prepared twice a year for the Security Council, which has imposed tough sanctions on North Korea because of its nuclear and ballistic-missile programs.

But the forthcoming report paints an especially damning picture of North Korea’s ability to evade international sanctions. It also comes at a critical moment in Washington’s diplomatic effort to eliminate North Korea’s nuclear-weapons programs and long-range missile capabilities.

An expanded version of this report appears on WSJ.com.

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