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Governments on both sides of the North Pacific may soon have stronger policies toward North Korea than they have in years. The question is how far democratic capitals will press North Korea to renounce its nuclear weapons programs. A key test is whether they can maintain pressure until the Pyongyang regime verifiably ends its misconduct. This is no small threat; Pyongyang has recently tested nuclear and ballistic missile weapons, not to mention its nuclear technology proliferation to terrorist-supporting states and its infamous human-rights abuses.

The U.S. is focusing, for now, on financial sanctions. On June 30, the U.S. Treasury Department froze the assets of an Iranian company that provided support to a North Korean bank involved in proliferation. The U.S. State Department...