South Korea is warning its communist northern neighbour that its plans to launch a long-range rocket later this month will lead to more sanctions and isolation. About 100 anti-North Korea activists protested in Seoul on Thursday, denouncing the project and the north’s leader Kim Jong Un. Pyongyang has confirmed it intends to launch a rocket this month, saying it wants to put a communications satellite into orbit. Such a move would be in defiance of a UN ban. A similar launch in April failed. The US sees such attempts as a cover for testing missiles. Japan has mobilised three destroyers from a naval base in preparation. Missile defence systems have been put in place, including around the Defence Ministry in Tokyo. On Wednesday NATO warned North Korea its plans risked aggravating tensions in the region. Russia and China have also urged restraint.