We arranged that Kissinger  would fly to Vietnam early in July and then stop in Pakistan on the way back. There he would develop a stomachache that would require him to stay in bed and not be seen by the press. Then, with President Yapha's help, he would be taken to the airport where a Pakistani jet would fly him over the mountains to China. Kissinger's trip was given the name Polo after Marco Polo, another Western traveler who made history by journey in China. Everything went quite smoothly. His slight illness in Islamabad received only small attention from reporters covering him. They accepted the story that he would be kept shut up for at least a few days and began making arrangements for their own activities. Because of the need for complete secrecy and the lack of any direct communication facilities between Beijing and Washington, I knew that we would have no word from Kissinger while he was in China. Even after he had returned to Pakistan, it would still be important to keep it secret, so before Kissinger left, we agreed on a single code word - Eureka - which he would use if his missions were successful and the presidential trip had been arranged. On July 11, Al Haig, who knew our code work, phoned to say that a cable  from Kissinger had arrived. "What's the message?" I asked. "Eureka". he replied. Washington would have no word from Kissinger while he was in China, mainly because   _  .
the trip must be kept secret president Yapha would not fly together with Kissinger communication between China and Islamabad was impossible Al Haig would phone to the author to tell him about Kissinger's trip