The Pentagon today formally launched a competition for a Next-Generation Interceptor, the most significant overhaul of the nation's missile defense system since 2004, setting in motion a high-stakes acquisition that could leave the United States vulnerable to North Korean threats if the project is delayed and promising, but unproven, back-up capabilities don't materialize as planned. The Missile Defense Agency today published a classified final request for proposals for the NGI, a multibillion- dollar acquisition that is expected to draw as...