WASHINGTON - The bilateral relationship between the United States and China is both comprehensive and important and has the ability to shape the 21st century, President Barack Obama told China's new ambassador Zhang Yesui on Monday.

The relationship reflects the deep ties between the two peoples who share a history far older than the 31 years of the formal diplomatic relations between the two countries, Obama said while accepting the Letter of Credence of the Chinese envoy.

He also said the two countries face shared regional and global challenges including stemming the proliferation of nuclear weapons, ensuring regional peace and stability and addressing climate change, which demand combined and immediate efforts.

"President Hu and I agreed last year that out two countries should build a positive, cooperative and comprehensive relationship for the 21st century, and we will both take concrete actions to steadily build a partnership to address common challenges," he said.

"I welcome a China that is a strong, prosperous and successful member of the international community," Obama said. "Now is the time for our two great nations to join hands and commit to creating a prosperous future for our children."

Obama reaffirmed that the US position on one-China policy is unchanged.

Zhang Yesui said good bilateral ties between China and the United States conform with the fundamental interests of the two peoples and are conducive to peace, stability and development in the Asia-Pacific region and the world as a whole.

China is ready to work with the United States to strengthen dialogue, mutual trust and cooperation while respecting each other's core interests and major concerns in order to build a positive, cooperative and comprehensive relationship for the 21st century, Zhang said.