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 Tuesday, 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, which appears to be the first to cross over Japan since 2009, will rattle a region worried that each new missile test puts the North a step closer toward its goal of an arsenal of nuclear missiles that can reliably target the United States. It appeared to be the North’s longest-ever missile test, but South Korean officials couldn’t immediately confirm.

North Korean missile launches have been happening 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. This missile landed nowhere near Guam, which is about 1,550 miles south of Tokyo, but the length of Tuesday’s launch 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.

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.”

Tuesday’s launch comes days after the North fired what was assessed as three short-range ballistic missiles into the sea and a month after its second flight test of an intercontinental ballistic missile.

South Korea’s Foreign Ministry warned that the North will face a “strong response” from the U.S.-South Korean alliance if provocations continue. The ministry also urged Pyongyang to accept talks over its nuclear program and acknowledge that abandoning its nuclear ambitions is the only way to guarantee its security and economic development.