SEOUL, South Korea — Satellite images show that North Korea has halted work at a complex believed to have been intended to allow it to launch bigger and longer-range rockets, a Washington-based research organization reported on Tuesday. Connect With Us on Twitter Follow @nytimesworld for international breaking news and headlines. Twitter List: Reporters and Editors The organization, the U.S.-Korea Institute at Johns Hopkins University, and others have been using commercial satellite imagery to monitor the complex, the Tonghae Satellite Launching Ground, in northeastern North Korea. They have previously detected the building of a new launching pad, missile assembly building and launch control…