South Korea's and Japan's militaries say North Korea has again test-fired a ballistic missile, which flew an estimated 40 minutes before landing in the Sea of Japan. It is the 12th provocation of the year, breaking United Nations resolutions barring such tests.The move by Pyongyang comes following a White House summit between President Trump and South Korean President Moon Jae-in, in which the two countries pledged to coordinate on North Korea policy and continue a security alliance that has lasted more than 60 years.South Korean president Moon Jae-in assembled the country's national security team for an emergency meeting.Trump responded to the test in tweets. Earlier he had indicated the reliance on China to help curb Pyongyang "hasn't worked out," and in two successive tweets following the morning missile launch, Trump seemed to poke fun at the North Korean leader, Kim Jong Un. The tweets read: