SEOUL (AP): The United States flew long-range B-1B bombers in a show of force against North Korea on Tuesday, days after the powerful sister of North Korean leader Kim Jong Un vowed to resist a US-led push to eliminate the North's nuclear programme.

North Korea often reacts to the US deployment of B-1B bombers and other powerful military assets with missile tests and fiery rhetoric.

Tuesday's flyover of the US bombers could draw an angrier response because it happened when North Korea was marking a key anniversary — the 113th birthday of state founder Kim Il Sung, the late grandfather of the current leader.

South Korea's Defence Ministry said the US bombers participated in a South Korea-US aerial drill over the Korean Peninsula to strengthen the allies' combined operational capability and demonstrate their deterrence capability against North Korea's advancing nuclear programme.

A ministry statement said South Korean F-35 and F-16 fighter jets and American F-16 fighter jets also took part in the training. It said South Korea and the US will continue to expand their joint military exercises to respond to North Korean nuclear threats.

It was the second time a US B-1B's had participated in a drill with South Korea since President Donald Trump began his second term in January.

In February, North Korea's Defence Ministry slammed the B-1B's earlier flyover as proof of intensifying US-led provocations since Trump's inauguration. It pledged to counter the strategic threat of the US with strategic means.

Days later, North Korea test-fired cruise missiles in what it called an attempt to show its nuclear counterattack capability.

Trump has repeatedly said he will reach out to Kim Jong Un to revive diplomacy. North Korea hasn't directly responded to Trump's outreach.

Last Wednesday, Kim Yo Jong — Kim's sister and a senior official — derided the US and its Asian allies over what she called their “daydream” of denuclearising the North, insisting that the country will never give up its nuclear weapons programme.

Her statement came as a response to a recent meeting among the top diplomats of the United States, South Korea and Japan where they reaffirmed their commitment to push for the North's denuclearisation.

The Kim Il Sung birthday, called “the Day of Sun,” is one of the most important holidays in North Korea, where a state-sponsored cult of personality treats key members of the ruling Kim family like gods.

On Tuesday, the country's main Rodong Sinmun newspaper issued an editorial urging the public to rally behind Kim Jong Un to achieve a national prosperity. In recent days, North Korea has held seminars, performances and other events commemorating the founder's achievements.