North Korea launched a long-range ballistic missile into the sea off its east coast on Saturday, after Pyongyang warned of a strong response to the upcoming U.S.-South Korea military drills.

Saturday’s long-range missile was launched from the Sunan area near Pyongyang, South Korea’s military said. Sunan is the site of the Pyongyang International Airport, where North Korea has carried out most of its recent intercontinental ballistic missile (ICBM) tests.

Japanese authorities reported the missile splashed into the waters inside Japan’s exclusive economic zone more than an hour after it was launched, suggesting the weapon was one of the North’s largest missiles.

North Korea’s first missile firing since January 1 comes after Pyongyang threatened on Friday an “unprecedentedly persistent and strong” response as South Korea and the United States gear up for annual military exercises, which are part of their efforts to fend off the North’s growing nuclear and missile threats.

Nuclear-armed North Korea fired an unprecedented number of missiles last year, including intercontinental ballistic missiles (ICBMs) that could strike anywhere in the United States, while resuming preparations for its first nuclear test since 2017.