The U.S. sent two B-1B bombers from Guam to buzz the Korean Peninsula following the isolated nation’s test this week of an intercontinental ballistic missile that analysts say is capable of striking Alaska.

The show of force was part of a 10-hour sequenced bilateral mission with South Korean and Japanese fighter jets on Friday.

According to a statement by the U.S. Pacific Command, the drills were “in response to a series of increasingly escalatory actions by North Korea, including the ICBM test.”

“North Korea’s actions are a threat to our allies, partners and homeland,” said Gen. Terrence O’ Shaughnessy, Pacific Air Forces commander. “Let me be clear, if called upon we are trained, equipped and ready to unleash the full lethal capability of our allied air forces.”

The statement said the B-1Bs flew to the Korean Peninsula, where they were joined by South Korean F-15 fighters and U.S. Air Force F-16 fighters. The B-1Bs practiced attack capabilities by releasing inert weapons at a firing range in South Korea.

Quoting South Korean Air Force officials, the Yonhap news agency said the U.S. bombers had apparently entered from the Sea of Japan and flew northward near the Military Demarcation Line in a show of force against the North. The report said the bombers were later joined by the South Korean fighters in a drill aimed at attacking key North Korean facilities.

“U.S. bombers and Republic of Korea fighters are just two of many lethal military options at our disposal,” U.S. Forces Korea deputy commander Lt. Gen. Thomas Bergeson said in a statement.

Before embarking on their return to Guam, the B-1Bs also flew and integrated with Air Self-Defense Force F-2 fighters over the East China Sea.

U.S. Forces Japan commander Lt. Gen. Jerry P. Martinez said the exercises highlighted the two allies’ bolstered military ties, which he said were “stronger than they have ever been.”

Despite growing military pressure, North Korea vowed late Friday that it would not halt its nuclear or missile development programs, reiterating that the ICBM test had been a response to “hostile U.S. policy.”

“As has been declared by respected Supreme Leader Comrade Kim Jong Un, the DPRK will neither put its nukes and ballistic missiles on the negotiating table in any case nor flinch even an inch from the road of bolstering its nuclear force unless the hostile policy and nuclear threat of the U.S. against the DPRK are thoroughly eradicated,” the official Korean Central News Agency quoted a spokesman from the North’s Foreign Ministry as saying.

“The U.S. will receive more ‘gift packages’ of different sizes from the DPRK in endless succession, as it tries harder to destroy, by means of sanctions and pressure, the overall national power and strategic position of the DPRK which have been drastically boosted.”

DPRK is the acronym for the North’s formal name, the Democratic People’s Republic of Korea.

Friday’s drills came just a day after the U.S. flew two B-1Bs over the South China Sea, part of separate operations intended to demonstrate Washington’s commitment to freedom of navigation in the contested waters and airspace.

China, which claims almost all of the strategic waterway, blasted the move, with Foreign Ministry spokesman Geng Shuang maintaining that freedom of navigation or overflight in the East and South China Seas was not a problem.

“But China resolutely opposes individual countries using the banner of freedom of navigation and overflight to flaunt military force and harm China’s sovereignty and security,” he said.

Beijing has built a string of militarized outposts on its man-made islets in the South China Sea’s Spratly chain as it seeks to reinforce effective control of much of the waterway, through which $5 trillion in trade passes each year. The Philippines, Vietnam, Malaysia, Taiwan and Brunei also have overlapping claims.

Ahead of the foray over the South China Sea, the Guam-based bombers held the U.S. Air Force’s first nighttime joint exercises with fighter jets from the Air Self-Defense Force. Those exercises were held over the East China Sea, where China is involved in a separate territorial disputed over the Japanese-controlled Senkaku Islands, known in China as the Diaoyus.

News of the bombers’ flight also came as U.S. President Donald Trump and his Chinese counterpart, Xi Jinping, prepared to meet on the sidelines of a Group of 20 summit in Germany. North Korea’s missile and nuclear programs were expected to top the agenda, and Trump was expected to urge China to do more to pressure Pyongyang.