US Air Force bombers and fighter jets have flown off North Korea's coast in what the Pentagon has called a "clear message".

The fleet of B-1B Lancer bombers was escorted by the F-15C fighter jets over international waters on Saturday.

The Pentagon called it an attempt to demonstrate the range of military options available to President Donald Trump.

It is also the farthest north of the country's Demilitarised Zone (DMZ) that any US military plane has flown over in the 21st century.

Pentagon spokeswoman Dana White said it underscores "the seriousness with which we take North Korea's reckless behaviour".


North Korea responds to Trump threats

This isn't the first demonstration of force from the US military in recent weeks.

Last week, Sky News joined troops from the 2nd Infantry Division of the US Eighth Army, the country's major ground combat unit on the Korean Peninsula, for their "Warrior Strike" operation.

The US and South Korea are currently conducting a series of joint drills close to the Korean border.

Pyongyang routinely describes these drills as acts of aggression and rehearsal for invasion.

Saturday's jet patrol comes after officials and experts concluded a small earthquake registered near North Korea's nuclear test site was likely not man-made.

Image: The tremor was detected near where North Korea recently conducted a nuclear test

There were fears Pyongyang could have exploded another nuclear bomb just weeks after its last one.

When the tremors were first reported earlier, China said it believed they may have been caused by an explosion.

But the country's monitoring centre later went on to say the magnitude 3.4 quake was not the result of a fresh missile test.

The flight demonstration follows a week of tensions between Washington and Pyongyang, with Mr Trump calling the North Korean leader a madman", and Kim Jong Un dubbing the US President a "mentally deranged dotard".