North Korea test-fired a medium-range ICBM that flew over northern Japan.  It was the fourth time in history that a North Korean missile violated Japanese airspace.

ABC News:

"We assess North Korea conducted a missile launch within the last 90 minutes," Col. Rob Manning, the director of press operations at the Department of Defense, said Monday evening in a statement. "We can confirm that the missile launch by North Korea flew over Japan. We are in the process of assessing this launch.

"North American Aerospsace Defense Command, or NORAD, determined the missile launch from North Korea did not pose a threat to North America. We are working closely with Pacific Command, Strategic Command and NORAD, and we'll provide an update as soon as possible," he added.

Japan's Prime Minister Shinzo Abe briefly addressed the launch, saying the country will be collecting more information, according to NHK, Japan's national public broadcasting organization.

The missile, which was launched early Tuesday local time, landed in the ocean, said Yoshihide Suga, Japan's chief Cabinet secretary, NHK reported.

"Nothing seemed have dropped on Japanese soil," Suga said.

"We will be working with Korea and other nations and gather information to secure the population of Japan," he added, according to NHK. It was the 13th launch by North Korea this year.

NHK reported the Japanese government issued a warning to people living in northern prefectures to take cover near strong structures after reports of the launch.

North Korean ballistic missiles have passed Japanese airspace at least four times in the past.

The last time a North Korea missile passed over Japanese airspace was February 2016, over islands in south Japan. At that time, North Korea said it was launching a satellite, the same explanation the country gave on two other occasions in 2012 and 2009.

Obviously, this ratchets up tensions in the region, a point that Japanese Prime Minister Abe made when he expressed his country's outrage and the provocative act:

CNN:

Soon after the launch, Abe called it a "unprecedented serious and grave threat to Japan" that "significantly undermines the peace and security of the region."

The Japanese leader said he spoke with US President Donald Trump for 40 minutes.

"Japan and the US completely agreed that an emergency meeting at the UN Security Council should be held immediately and increase the pressure towards North Korea."

Trump reiterated that the United States "stands with Japan 100%," Abe said.

While the missile flew over Japanese territory, one analyst said it wasn't necessarily intended as a threat to Japan.

"If they're going to launch to a distance they've got to go over somebody. It looks to me like a risk reduction measure, they want to reduce the populated areas they fly over just in case anything goes wrong," said Joshua Pollack, a senior research associate at the James Martin Center for Nonproliferation Studies.

Soon after the launch, Abe called it a "unprecedented serious and grave threat to Japan" that "significantly undermines the peace and security of the region."

The Japanese leader said he spoke with US President Donald Trump for 40 minutes.

"Japan and the US completely agreed that an emergency meeting at the UN Security Council should be held immediately and increase the pressure towards North Korea."

Trump reiterated that the United States "stands with Japan 100%," Abe said.

While the missile flew over Japanese territory, one analyst said it wasn't necessarily intended as a threat to Japan.

"If they're going to launch to a distance they've got to go over somebody. It looks to me like a risk reduction measure, they want to reduce the populated areas they fly over just in case anything goes wrong," said Joshua Pollack, a senior research associate at the James Martin Center for Nonproliferation Studies.

China is proving its uselessness in this crisis by blaming the U.S. and South Korea for the launch, citing new sanctions and other provocative acts to excuse the behavior of North Korea. 

Did Kim order a test launch while America was preoccupied with Hurricane Harvey?  The possibility cannot be dismissed, but ordinarily, these tests are planned many days in advance. 

Kim is now on shaky ground.  He's just about played out the string on what he can reasonably expect to get away with.  From here on out, his calculations on U.S. reaction to a missile or nuke test will be far less certain.  The launch over Japan served only to bring the U.S. and South Korea closer to the conclusion that while military action on the Korean peninsula would be catastrophic, not doing anything would be worse.