At this time Soviet officials began to sound out discretely how the West might react if the Soviet Union were to attack China’s nuclear installations. The high stakes with which Mao had been playing in confronting both the superpowers had finally reached the ultimate crisis. The various attempts to find counterweights in the Third World and among the smaller capitalist powers had failed. The attempts to signal to the United States in the autumn of 1968 that the PRC wished to resume the dialogue in the wake of the Soviet invasion of Czechoslovakia had gone unheeded. From that point, however, the PRC broke away from its self-inflicted isolationist stance to encourage a new wave of diplomatic recognition by many countries, including those from the West. It was not until 1969, as a result of the fighting, that President Nixon and his national security adviser, Kissinger, responded. Meanwhile, if Beijing had been pleased by the Nixon Doctrine, which acknowledged that the United States would no longer commit land forces to fight wars in Asia, it was less pleased by the US-Japan agreement about the reversion of Okinawa, which included Japanese claims that its security interests included South Korea and Taiwan.