Why did US foreign policy with China change during Detente?

Nixon was the US leader during Detente, and he shifted the US foreign policy from an attack position to a defense stance. This was because he wanted to contain communism whilst maintaining peaceful coexistance with the USSR. This shift in foreign policy was for economic reasons on the one hand, as the combinaton of funding the Bretton Woods system, the Arms Race and the Vietnam War was unsustainable; but it was also for political reasons which centered around the Sino-Soviet split and the window of opportunity it left for the USA to embark on more peaceful relations with the USSR. To make the most of this opportunity, Nixon decided to launch Triangular Dimplomacy in an attempt to entice the USSR into peace negotiations by allying with China and playing on the USSR's insecurities. Thus, trade between the US and China increased from 0$ in 1970 to 2billion$ in 1979. China was also allocated a place on the UN Security board in 1971, and Nixon shook Zhou Enlai's hand on a visit to China, which was symbolic as this had not been done in many years. Therefore, the US foreign policy with China drastically changed in the period known as Detente because Nixon was attempting to lure the USSR into negotiations by bettering its relationship with China, which Nixon knew would play on the USSR's insecurities of having no truly powerful allies.