After North Korea's previous missile test, the U.S. also proposed a press statement, but diplomats said China insisted on language linking it to U.S. plans to place a high-tech missile defense system in South Korea. The Security Council in March imposed the toughest sanctions on North Korea in two decades, reflecting growing anger at Pyongyang's latest nuclear test and rocket launch in defiance of a ban on all nuclear-related activity. A North Korean nuclear test in January and a series of missile launches by Pyongyang have all been carried out in violation of Security Council resolutions.