North Korea fired a ballistic missile into its eastern waters, officials in Seoul said, hours after it threatened a “harder military response” to efforts by the United States to boost its security presence in the region. South Korea’s Joint Chiefs of Staff said the short-range ballistic missile was fired from North Korea’s Wonsan region on Thursday. The missile flew about 240 kilometers (149 miles) and reached an altitude of 47 kilometers (29 miles), the JCS said, adding that shortly before the launch, the South Korean and U.S. militaries had conducted a “pre-planned” missile defense exercise. . The South Korean military will continue to maintain a firm posture of readiness, it said. Pyongyang has tested a record number of missiles this year, including a possible failed intercontinental ballistic missile, while Washington and Seoul have expanded the scope and scale of their joint military exercises. Some of the exercises involved Japan. Amid the tensions, the leaders of the US, South Korea and Japan held trilateral talks on the sidelines of the East Asia Summit in Cambodia last week and pledged to work together to further “enhance deterrence”. In a statement after the talks, US President Joe Biden, South Korean President Yoon Suk-yeol and Japanese Prime Minister Fumio Kishida “strongly condemned” North Korea’s “unprecedented number of ballistic missile launches” and pledged to “create more closer tripartite ties. in the field of security and beyond”. They also warned Pyongyang against a seventh nuclear test, with Biden reiterating that the US commitment to defend Seoul and Tokyo is “backed by the full range of capabilities, including nuclear”. North Korea condemned the three-way summit on Thursday, with Foreign Minister Choe Son Hui saying the three countries’ “aggression war drills” would not rein in Pyongyang but would pose a “more serious, realistic and unavoidable threat”. against them. “The more intense the US is in its ‘enhanced offer of extended deterrence’ to its allies and the more it steps up provocative and bluffing military activities, the tougher the DPRK’s military response will be,” Choe said in a statement carried by the official KCNA news. agency. She referred to her country by the initials of its official name, the Democratic People’s Republic of Korea. “The US will be well aware that they are taking a gamble that they will surely regret,” he said. Choe added that the North’s military activities are “legitimate and just responses” to the US-led drills. Analysts said the signals coming from Pyongyang were important given last week’s regional summit and Chinese President Xi Jinping’s participation after years of self-imposed pandemic isolation. China is the isolated North’s main ally and trading partner. “Beijing may not immediately become more cooperative in dealing with North Korea, even after the Kim regime conducts another nuclear test,” Leif-Eric Easley, a professor at Ewha University in Seoul, told Al Jazeera by email. “But at some point, Chinese interests will prefer to put pressure on Pyongyang rather than face a more strategically united US, South Korea and Japan.”