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It was the farthest north of the Demilitarised Zone (DMZ) that US fighters or bomber aircraft have ever flown this century.
The flight underscored "the seriousness with which we take North Korea's reckless behaviour," the Pentagon said.
"This mission is a demonstration of US resolve and a clear message that the President has many military options to defeat any threat.
"North Korea's weapons programme is a grave threat to the Asia-Pacific region and the entire international community. We are prepared to use the full range of military capabilities to defend the US homeland and our allies," Pentagon spokeswoman Dana White said in a statement.
There has been name-calling and heightened tensions between Washington and Pyongyang this week as the UN met in New York, CNN reported.
At the UN, North Korea's Foreign Minister Ri Yong-ho said US President Donald Trump was on a "suicide mission".
Ri's comments to the General Assembly mimicked Trump's remarks at the UN on Tuesday, when he called North Korean leader Kim Jong-un a "rocket man on a suicide mission".
Earlier this week, Ri had also said that his country could test a powerful nuclear weapon over the Pacific Ocean in response to Trump's threats of military action.
The minister's remarks came shortly after Kim made an unprecedented televised statement, accusing Trump of being "mentally deranged".
Meanwhile, a shallow 3.4-magnitude tremor was detected near North Korea's nuclear test site on Saturday morning, but experts believe it was a natural earthquake.