The United States military and Pacific allies have conducted air drills over the Korean peninsula in conjunction with computer simulations just days after North Korea added tension to already stressed relations by firing a missile over Japan.

The air drills involved two supersonic US B-1B bombers and four US health F-35B jets alongside South Korean and Japanese fighter jets. The exercise — which brought nuclear capable bombers over the Korean peninsula — came at the tail end of annual joint US-South Korea military exercises.

“North Korea’s actions are a threat to our allies, partners, and homeland. And, their destabilising actions will be met accordingly,” US General Terrence J O’Shaughnessy, the commander of Pacific Air Forces, said during an unscheduled visit to Japan.

“This complex mission clearly demonstrates our solidarity with our allies, and underscores the broadening cooperation to defend against this common regional threat. Our forward deployed force will be the first to the fight, ready to deliver a lethal response at moment’s notice if our nation calls.”

North Korea has been flagrantly displaying its progress on its quest to develop weapons systems capable of launching a nuclear-tipped missile capable of hitting the US, and has recently threatened Guam, a US territory. Before the missile test over Japan, intelligence had indicated hat the country was capable of producing miniaturised nuclear warheads that could be put in missiles, and North Korea had repeatedly tested long-range intercontinental ballistic missiles.

“The US imperialists and the South Korean puppet forces do not hide their bellicose nature, claiming that the exercises are to ‘counter’ the DPRK’s ballistic rocket launches and nuclear weapons development,” North Korea’s KCNA news agency said, referring to the acronym for the Democratic People’s Republic of Korea, the official name for the country.

In pictures: North Korea military drill Show all 8 1 /8 In pictures: North Korea military drill In pictures: North Korea military drill North Korea's leader Kim Jong Un watches a military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) is seen in this handout photo by North Korea's Korean Central News Agency (KCNA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) is seen in this handout photo by North Korea's Korean Central News Agency (KCNA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video

“But the wild military acts of the enemies are nothing but the rash act of those taken aback by the intermediate-to-long range strategic ballistic rocket launching drill conducted by the army of the DPRK as the first military operation in the Pacific,” the news agency continued.

North Korea’s open development of warheads that could threaten the US have led to an increasingly strained relationship between Washington and Pyongyang — two capitals that had anything but a good relationship before. As a result, President Donald Trump has threatened that North Korea would face “fire and fury” if it continued to threaten the US, and indicated that the US military was ready with military options if the aggression continues.

Mr Trump has since then made clear that he is at least considering a military response to North Korea’s missiles, however it is uncertain if there is strong support for action like that in his administration. Since the aggression began, the US has imposed sanctions on North Korea, impacting a significant portion of the country’s economy.

The President said this week that “talking is not the answer” to the conflict with North Korea, but his Defence secretary, Jim Mattis, told reporters just hours later that the US had not run out of diplomatic options for dealing with the Korean adversary.

“We are neer out of diplomatic solutions,” Mr Mattis said. “We continue to work together, and the minister and I share a responsibility to provide the protection of our nations, our populations, and our interests.”