SEOUL, South Korea

North Korea fired a ballistic missile from its capital Pyongyang that flew over Japan before plunging into the northern Pacific Ocean, officials said today, an aggressive test-flight over the territory of a close U.S. ally that sends a clear message of defiance as Washington and Seoul conduct war games nearby.

Seoul’s Joint Chiefs of Staff said the missile traveled around 1,677 miles and reached a maximum height of 341 miles as it flew over the northern Japanese island of Hokkaido. The launch appeared to be the first of a North Korean missile to cross over Japan, though some rockets it said were used to put satellites into space have done so. It also appeared to be the North’s longest-ever missile test, but South Korean officials couldn’t immediately confirm.

Each new test puts the North a step closer toward its goal of an arsenal of nuclear missiles that can reliably target the United States. The North has launched at an unusually fast pace this year, and some analysts believe the North could have viable long-range nuclear missiles before the end of President Donald Trump’s first term in early 2021.

The South Korean military said it is analyzing the launch with the United States and has strengthened its monitoring and preparation in case of further actions from North Korea. Analysts speculate the North may have tested a new intermediate range missile that Pyongyang recently threatened to fire toward the U.S. territory of Guam, which hosts a major military base. This missile landed nowhere near Guam, which is about 1,550 miles south of Tokyo, but the length of its flight path may have been designed for the North to show it could follow through on its threat. Seoul says the missile was launched from Sunan, which is where Pyongyang’s international airport is, opening the possibility that North Korea launched a road-mobile missile from an airport runway.

North Korea will no doubt be watching the world’s reaction to see if it can use today’s flight over Japan as a precedent for future launches. Japanese officials said there was no damage to ships or anything else reported. Japan’s NHK TV said the missile separated into three parts. “We will do our utmost to protect people’s lives,” Prime Minister Shinzo Abe told reporters. “This reckless act of launching a missile that flies over our country is an unprecedented, serious and important threat.”

North Korea typically reacts with anger to U.S.- South Korean military drills, which are happening now, often testing weapons and threatening Seoul and Washington in its state-controlled media. But animosity is higher than usual following threats by Trump to unleash “fire and fury” on the North, and Pyongyang’s stated plan to consider firing some of its missiles near Guam.

North Korea first fired a rocket over Japanese territory in August of 1998 when a multistage rocket that outside experts called “Taepodong 1” flew about 932 miles before landing in the Pacific Ocean. The North later said it launched a satellite.

North Korea flew another rocket over Japan again in April 2009 and said that, too, was carrying a satellite. The North claimed success, but the U.S. North American Aerospace Defense Command says no satellite reached orbit. The United Nations has repeatedly condemned North Korean satellite launches as covers meant to test banned long-range missile technology. Some parts of a space launch vehicle reportedly flew over Okinawa last year after separating from the rocket.

Pyongyang regularly claims the U.S.-South Korean military exercises are an invasion rehearsal, although analysts say the North’s anger is partly because the impoverished country must react with its own expensive drills and weapons tests. The allies say the war games are defensive and meant to counter North Korean aggression.

North Korea’s U.N. ambassador, Ja Song Nam, wrote recently that the exercises are “provocative and aggressive” at a time when the Korean Peninsula is “like a time bomb.”