"Let's go back to 1971, that's when the pingpong diplomacy first started and that's when we became friends. So our two greatest countries should keep cooperating and make our cooperation even stronger," Liu said.

China and the United States began their Olympic relationship in Lake Placid in 1980, but China won its first gold medal in the Los Angeles Games in 1984, in men's free pistol.

Ueberroth said that when 100 nations agreed to a retaliation boycott of the Los Angeles Games, China refused, and later all but six of the nations who had refused attended the Los Angeles Games. China is largely credited with bolstering the Los Angeles Games, which followed the U.S.-led boycott of the 1980 Moscow Games.

"I am grateful to China for making the 1984 Games so successful, and I would do anything to help make the Beijing Games successful," Ueberroth said.

After the signing ceremony, the U.S. Olympic Committee presented Liu a torch from the 1984 Olympics that was signed by Rafer Johnson, who lit the torch at those Games. Ueberroth said it was one of six torches that remained from those Games.

Liu presented Ueberroth a small banner bearing the logo of the 2008 Beijing Olympics before the two had champagne together.

Also at the signing ceremony was Chinese volleyball star Sun Junfang, former captain of the women's national team and a participant in the 1984 Olympics.