Following the Indonesian crisis in 1958, which had included the Permesta rebellion in eastern Indonesia and the declaration of the PRRI, a rebel revolutionary government based in Sumatra; Indonesia had emerged as a notable and rising military power in Southeast Asia. With the influx of Soviet arms aid, Indonesia was able to advance its diplomatic claims to Netherlands New Guinea more forcefully. The diplomatic dispute reached its climax in 1962 when Indonesia launched a substantial campaign of airborne and seaborne infiltrations upon Netherlands New Guinea. While the infiltration forces were soundly defeated by Dutch and indigenous forces, Indonesia was able to lend credence to the threat of an Indonesian invasion of Netherlands New Guinea. The Dutch, facing mounting diplomatic pressure from the Indonesians and the Americans, who were anxious to keep Indonesia from becoming Communist aligned, yielded and agreed to a diplomatic compromise, allowing the Indonesians to gain control of the territory in exchange for pledging to hold a self-determination plebiscite (the Act of Free Choice) in the territory by 1969. Thus by the close of 1962, Indonesia had achieved a considerable diplomatic victory, which possibly emboldened its self-perception as a notable regional power. It was in the context of this recent diplomatic victory that Indonesia cast its attention to the British proposal for a unified Malaysian state.