[Cheburashka]

At the time Nixon first came into office there were informal diplomatic feelers from the Soviets along the lines of "How would the United States view it if the Soviet Union were to invade China? Just as a hypothetical, of course."
Nixon had the State Department respond whenever this came up that the U.S. would look at any invasion in the most negative light.
Both sides of these conversations probably got back to the Chinese and allowed Nixon and Kissinger to improve relations with the Chinese.
You should remember that Nixon was trying to extract the U.S. from the Viet Nam War and, at least in the seventies it was looking as if the Soviet Union was on the verge of pulling ahead of the U.S. militarily. The understanding with the Chinese helped to keep the Soviets in check.
The Soviets invading Afghanistan and getting themselves bogged down there, and the Presidency of Ronald Reagan and the rebuilding of American military power were still in the future.

[Michael.SF.]

Thanks for the added information. Actually, my comment was more tongue in cheek then serious. Nixon's policies regarding China did open the door for China to move forward in many areas. Nixon recognized the necessity of dealing with them.

But, I still do not trust them.