The United States is urging Americans in North Korea to get out before a travel ban goes into effect on September 1.

The State Department is issuing a new travel warning for North Korea that reflects the Trump administration's new travel ban. That ban was announced last month and was published Wednesday in the Federal Register. That triggers a month-long period before it takes effect.

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The warning says exceptions to the travel ban need special permission that will only be granted "under very limited circumstances." The State Department says it doesn't yet know when it will release information on how to apply for an exception.

Previous US travel warnings also urged Americans not to travel to North Korea.