Because for decades the world did nothing

Think of Madeleine Albright clinking champagne glasses with Kim Jong-il as you take this development in:

North Korea defiantly celebrated its fifth nuclear test Friday, claiming that it can now make warheads small enough to fit onto a missile and warning its "enemies" — specifically, the United States — that it has the ability to counter any attack.

The test appeared to be much bigger than North Korea's previous detonations. And although the North's claim that it mastered the technology to miniaturize nuclear weapons could not be verified — and Pyongyang has a track record of exaggeration — Friday's test underscored the fact that Kim Jong Un's regime was continuing to make progress on its nuclear and missile programs despite waves of international sanctions and condemnation.

"This is our response to hostile powers, including the United States. We are sending out a message that if the enemies attack us, we can counterattack," Ri Chun Hee, the veteran North Korean newsreader, said on state television. "We will continue taking measures to protect our dignity and our right to exist from the American threat."

The U.S. Geological Survey detected an artificial 5.3-magnitude earthquakenear North Korea's nuclear test site at exactly 9 a.m. local time on Friday, the 68th anniversary of the formation of the communist regime by Kim Il Sung, the current leader’s grandfather, and a national holiday.

“This is clearly a nuclear test,” said Jeffrey Lewis, director of the East Asia nonproliferation program at the James Martin Center for Nonproliferation Studies in Monterey, Calif. He estimated the size at between 10 and 20 kilotons. If confirmed, that would make this the biggest of North Korea’s five tests. January’s test was about six kilotons.

This occurred as the Most Equal Comrade was in Japan, his jet refueling on the way home from Laos, where he trashed the country over which he is tyrant and signaled the world once again that it cannot depend on post-America to guarantee its basic safety from nuclear annihilation.

UPDATE: Gordon Chang at the Daily Beast says that relations between China and post-America have everything to do with the timing of this test:

At the moment, Beijing is far more upset with Seoul than Pyongyang.

In July, South Korea and the United States announced they would deploy the American-made Terminal High Altitude Area Defense system on South Korean soil. Beijing is worried that THAAD’s high-powered radars will reach into China and could help the U.S. shoot down Chinese missiles. Washington denies that is the case and has been willing to share technical information, but Beijing has not been mollified.

Since the announcement, Beijing has taken a number of steps to snub the South diplomatically and undermine its economy.

With Beijing upset at Seoul, the North Koreans evidently think they can do what they want. On Monday, the North launched three medium-range, nuclear-capable Nodong missiles. The tests, on the second day of the China-hosted G20 summit, were conducted right after Chinese ruler Xi Jinping met on the sidelines of the event with South Korea’s president, Park Geun-hye. Clearly, Kim Jong Un was not worried that China would react unfavorably to the launches.

It’s clear the North Koreans know that as a general matter they have Chinese support. Trade across the Sino-Korea border is booming at the moment, an indication that Beijing is not enforcing Security Council Resolution 2270, the fifth set of U.N. sanctions on the North’s weapons programs.
Moreover, some of the traded items are clearly destined for Kim’s military. China, according to David Albright of the Institute for Science and International Security, did not interrupt the flow of materials and components for Pyongyang’s nuclear weapons program, such as cylinders of uranium hexafluoride. Also allowed in, worryingly, were vacuum pumps, valves, and computers.
The North Koreans know that Xi sees the U.S. as China’s main adversary, blocking Beijing’s ambitions in almost every direction.  That’s probably why President Obama and National Security Adviser Susan Rice got a rough reception on Saturday in Hanghzou as they arrived for the G20. Kim, seeing how Xi treated Obama, thought he could get away with delivering his own radioactive-laced snub.
Kim knows that Xi is not about to further goals, like the denuclearization of North Korea, that Washington promotes, and so Pyongyang thinks it has a big green light in its quest to possess the world’s most destructive weapons. 

Pyongyang will make fast progress in developing nukes—until the U.S. and the rest of the international community realize they have a China problem as much as a North Korean one. 

Everybody smells weakness.