The build-up to North Korea's launch, and possible reasons it failed

North Korea celebrated the "Day of the Sun" Saturday, marking the anniversary of the birth of the country's founder (and Kim Jong-un's grandfather), with a parade that included three missiles. One of those missiles was new, and appeared to be intercontinental in range, an expert told the NYT.

That celebration ended with the launch of a ballistic missile, from a submarine base on the East Coast, which exploded almost immediately.

• Kim was attempting a show of strength following a rhetorical battle with the US, in which Pyongyang said it was prepared for "nuclear war" with Washington.
• The US had positioned destroyers in the region to try and warn North Korea against a launch, and potentially to respond (though US officials had tamped down talk of a military response).
• Mike Pence was en route to South Korea at the time of the launch in part to discuss the nuclear issue.

NYT on why the launch might have failed:

As the North's skills grew, President Barack Obama ordered a surge in strikes against the nuclear launches, including through electronic-warfare techniques. It is unclear how successful the program has been, because it is almost impossible to tell whether any individual launch failed because of sabotage, faulty engineering or bad luck. But the North's launch-failure rate has been extraordinarily high since Mr. Obama first accelerated the program.