 Further strengthening of the union occurred on December 25, 1998, and in 1999.Under Putin, Russia has sought to strengthen ties with the People's Republic of China by signing the Treaty of Good-Neighborliness and Friendly Cooperation as well building the Trans-Siberian oil pipeline geared toward growing Chinese energy needs.He also made a number of appearances in the media with President of the United States George W. Bush in which the two described each other as "friends".