However, the exhilaration on the part of the Thais and the Americans after Phoumi's success in retaking Vientiane was short-lived. Kong Le's neutralist troops who had escaped from Vientiane unscathed in mid-December soon joined the forces of the Pathet Lao on the Plaines des Jarres (PDJ). The North Vietnamese took advantage of the confused situation, and moved their troops into Laos to support the Pathet Lao. Together, they expelled all the remnants of the rightist troops present in the area. The worst fear for the Thais and the Americans, that the neutralists and the communists would unite against the rightists, came true.