Meanwhile, Ranariddh stepped up his attacks against Hun Sen, accusing him of harbouring plans to restore a Communist regime should the CPP win the next general election. At the same time Ranariddh attempted to persuade moderate leaders of the Khmer Rouge, including Khieu Samphan and Tep Kunnal, to join the NUF. Khieu Samphan accepted Ranariddh's overtures, and on 21 May 1997, put the support of his party, the Khmer National Solidarity Party (KNSP), behind the NUF. On 4 June 1997, Ranariddh and Samphan signed a communiqué pledging mutual support. Five days later, customs officials at Sihanoukville discovered a three-ton shipment of rocket launchers, assault rifles and handguns, labelled "spare parts" and consigned to Ranariddh. The rocket launchers were seized by Cambodian Air Force officers aligned to the CPP, while Royal Cambodian Armed Forces (RCAF) officials aligned to FUNCINPEC were allowed to keep the light weapons. In mid-June, Khmer Rouge radio, controlled by Khieu Samphan, broadcast a speech praising the KNSP-NUF alliance and calling for an armed struggle against Hun Sen. Fighting subsequently broke out between Ranariddh's and Hun Sen's bodyguards.