US Department of Defense: Our fighter jets flew near the North Korean border
US bombers flew near the east coast of North Korea to prove there was a military option to face any threat, the Pentagon said.
The flight was at the farthest point any US fighter or bomber ever had in the 21st century in the north of the demilitarized zone between the two Koreas, the ministry said.
Tensions have recently raged between the two countries over Pyongyang's nuclear and missile program.
At the UN General Assembly meeting, North Korea's foreign minister said US President Donald Trump was carrying out a "suicide mission".
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Ri Yong-ho's comments echoed Trump's remarks before the General Assembly on Tuesday, in which North Korean leader Kim Jong-un was described as a "rocket man" on a suicide mission.
Reem's "insults" Trump, "the psychologically insane and the paranoid," was an "irrefutable mistake that makes it inevitable that North Korea's missiles will hit the mainland of the United States."
The Korean minister said Trump would "pay a heavy price" for his speech, in which he also said he would "completely destroy" North Korea if the United States had to defend itself or its allies.
Shortly before his speech, the Pentagon said the review of the force had underscored the "seriousness" of the United States dealing with North Korea's "wrongdoing", calling the nuclear program "an overwhelming threat."
"This is a demonstration of the will of the United States and a clear message that President (Donald Trump) has military options to counter any threat," he said.
"They are ready to use our maximum military capability to defend the United States and our allies."
The US Air Force's P-1B Lancer on the island of Guam, accompanied by F-150C Eagle fighters from Okinawa, Japan, flew into international airspace, the Pentagon said.
The American bombers flew after a week of war between the leaders of the two countries.
North Korea's foreign minister has not commented on the Pentagon statement so far.
North Korea has refused to halt its missile and nuclear tests, despite successive UN sanctions. North Korea's leaders say nuclear capability is the only deterrent against the outside world that seeks to destroy our country.
After Pyongyang conducted its strongest nuclear test earlier this month, the Security Council passed a new package of sanctions against it.
In his response to the UN General Assembly meeting, North Korea's foreign minister stressed that the sanctions would not discourage his country from developing its nuclear program.
Meanwhile, an earthquake measuring 3.4 on the Richter scale near a nuclear weapons test site in North Korea Saturday, but experts believe the causes of the earthquake are normal.
The quake was recorded at a depth of less than 5 kilometers north of North Hamyong County, where the Bunggyi Re nuclear test site is located, according to the South Korean Meteorological Agency.
The US Geological Survey also said the quake occurred in the nuclear testing area, but added that its seismologists believed it had fallen at a depth of five kilometers.
South Korea said it had not detected any sound waves caused by artificial earthquakes in the area.
China's quake department said the earthquake was not caused by a nuclear explosion, as there were all indications that it was a natural quake.
The administration initially said it suspected the earthquake was the result of a bombing.
In a separate development, China announced it would cut North Korea's oil supplies and stop buying textiles under UN sanctions against Pyongyang.
China is North Korea's most important trading partner and one of its few sources of hard currency.
The ban on North Korea, the world's second-largest exporter of textiles, is expected to cost more than $ 700 million a year.
Cilia Hatton, a BBC journalist in Asia and the Pacific, says clothing is usually made in North Korea and finished in China, making the phrase "made in China" legal.
China said its restrictions on petroleum products would be applied on October 1, while restrictions on liquefied natural gas would be applied immediately.
Under the UN resolution, China will be able to export at least 2 million barrels of refined oil to North Korea annually from next year.