Japanese Prime Minister Junichiro Koizumi said on Wednesday he would not withdraw troops from Iraq despite a threat by a militant group to behead a Japanese hostage within 48 hours unless Tokyo pulled its forces out. "We cannot tolerate terrorism and we will not give in to terrorism," Koizumi told reporters. "We will not withdraw the (Japanese) Self-Defence Force." Japan has sent about 550 non-combat troops to southern Iraq to carry out humanitarian and reconstruction work.