Many countries around the world condemned North Korea's nuclear tests. The United Nations (UN) have tightened sanctions on North Korea's trade and banking. The UN demanded that the country retract its announcement of withdrawal from the Nuclear Non-Proliferation Treaty (NPT) and reaffirmed its decision that “the DPRK shall abandon all nuclear weapons and existing nuclear programs, in a complete, verifiable and irreversible manner.” Some countries including the U.S. have built missile defense systems and radar systems.