WASHINGTON -- U.S. President Donald Trump's national security adviser says the U.S. has a military option for North Korea, but that is not its preferred route.

H.R. McMaster spoke about North Korea Friday during a White House briefing about the upcoming UN General Assembly meeting next week.

One former top Trump adviser has said the U.S. is bluffing when it threatens military force against North Korea.

McMaster says North Korea is on track to having a nuclear weapon that could threaten its neighbours and the United States. McMaster said the U.S. has "run out of road."

McMaster says recently imposed UN sanctions on North Korea are just taking effect. He calls on all nations to enforce them and do everything they can to address the threat and prevent war.