THE United States has flown two supersonic bombers over the Korean Peninsula in a show of force against North Korea following the country's latest intercontinental ballistic missile test.

The B-1 bombers were escorted by South Korean fighter jets as they performed a low-pass over an air base near the South Korean capital of Seoul before returning to Andersen Air Force Base in Guam, the US Pacific Air Forces said in a statement.

It said the mission was a response to consecutive missile tests by North Korea this month.

Analysts say flight data from the North's second ICBM test, conducted on Friday night, showed a broader part of the mainland United States, including Los Angeles and Chicago, is now in range of Pyongyang's weapons.

"North Korea remains the most urgent threat to regional stability," General Terrence J O'Shaughnessy, Pacific Air Forces commander, said.

"Diplomacy remains the lead. However, we have a responsibility to our allies and our nation to showcase our unwavering commitment while planning for the worst-case scenario."

"If called upon, we are ready to respond with rapid, lethal and overwhelming force at a time and place of our choosing."

The United States often sends powerful war planes in times of heightened tensions with North Korea. B-1 bombers have been sent to South Korea for flyovers several times this year in response to the North's banned missile tests, and also following the death of a US college student last month after he was released by North Korea in a coma.

The Hwasong-14 ICBM, which the North first tested on July 4, is the highlight of several new weapons systems Pyongyang launched this year.

They include an intermediate range missile that North Korea says is capable of hitting Alaska and Hawaii, and a solid-fuel mid-range missile which analysts say can be fired faster and more secretly than liquid-fuel missiles.

Meanwhile, the US Missile Defence Agency said a Terminal High Altitude Area Defence, or THAAD, system located in Kodiak, Alaska, was successfully tested on Saturday night.

It said a medium-range ballistic missile was air-launched over the Pacific, and the THAAD system detected, tracked and intercepted the target.