U.S. Senator John McCain has raised doubts about the effectiveness of the U.S. tracking a North Korean-flagged ship.

The vessel "Kang Nam" is suspected of transporting weapons materials in violation of U.N. Security Council Resolution 1874, which was passed June 12th.

McCain said that China is the only nation that wields significant influence on the North. China’s role in tackling the North Korean nuclear issue is an important part of the U.S.-China relationship, he added.

At a news conference Thursday, the U.S. senator called the new U.N. resolution, which bans the operation of ships suspected of carrying nuclear-related materials, ‘toothless.’

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