nuclear test - North Korea

Why do they do the tests?

They need to conduct tests to perfect the technology, analysts say.

Some have speculated that the United States has tried to meddle with the program using cyber methods, which could halt progress.

The tests also are thought to be timed for maximum political impact -- a May launch coincided with the One Belt One Road summit in Beijing, an important project for Chinese President Xi Jinping, and a February launch happened as Japanese Prime Minister Shinzo Abe was visiting US President Donald Trump.

And the ICBM test came on July 4, Independence Day in the US.

All of this applies equally to the North's nuclear test program, which has typically followed a similar pattern.

Dramatic missile progress in 2017

North Korea’s efforts to develop a nuclear-armed intercontinental ballistic missile capable of hitting the US mainland have accelerated during the first year of Donald Trump’s presidency. The country’s leader, Kim Jong-un, has presided over a series of successful missile tests, including North Korea’s first launch of an ICBMon 4 July, a development he promised in a televised new year’s address. Like all tests, the missile came down in the sea but its trajectory was thought to place Alaska in range of a live strike.

SEOUL, South Korea — North Korea fired another ballistic missile over Japan on Friday, a direct challenge to the United States and China just days after a new sanctions resolution adopted by the United Nations Security Council that was intended to force the country to halt its accelerating nuclear and missile tests.

The missile was not aimed at the Pacific island of Guam, which President Trump had warned could prompt a military response after North Korea threatened to fire missiles into the sea near the island last month.Instead, it blasted off from near the Sunan International Airport north of Pyongyang, the North Korean capital, and flew about 2,300 miles directly east, flying over northern Japan and falling into the Pacific Ocean, according to the South Korean military. That is a slightly greater distance than between the North Korean capital and the American air base in Guam, and American officials, scrambling to assess both the symbolism and importance of the test, said it was clearly intended to make the point that the North could reach the base with ease.

One senior American military official called it a test shot that was also meant as a warning that the primary American bomber base in the Pacific, which would be central to any military action on the Korean Peninsula, was within easy reach of the North’s intermediate-range missiles. At the White House, the launching came at the end of the working day, and senior officials gathered in the Situation Room to weigh a response. But the Trump administration chose not to take out the missile on the launching pad, even though they saw it being fueled up a day ago. Vice President Mike Pence, officials said, was even shown images of the missile during a visit to one of the nation’s intelligence agencies.

Neither the United States nor Japan tried to shoot down the missile, perhaps because it was clear moments after the launching that it was not aimed at land. “The North American Aerospace Defense Command determined this ballistic missile did not pose a threat to North America,” Cmdr. Dave Benham, a spokesman for United States Pacific Command, said in a statement. It also concluded that the missile “did not pose a threat to Guam.”

Nonetheless, in Japan, an alert was issued on television and via cellphones, warning people to take shelter inside a building or underground. Japan said the missile landed in waters about 1,370 miles east of the northern Japanese island of Hokkaido. The launching appeared to answer a lingering question: whether Kim Jong-un, North Korea’s leader, would view the latest round of sanctions, passed unanimously by the Security Council, as a threat to his government or a reason to speed forward with his program. The test also appeared to move the North one step closer to showing that it could place a nuclear warhead atop a missile that could travel thousands of miles, a prospect that has rattled the region and posed a daunting foreign policy challenge to the Trump administration.