He hailed the dialogue as an "essential step forward in advancing a positive, constructive, and comprehensive relationship" between the two countries.

"Our countries have now shared relations for longer than we were estranged. Our people interact in so many ways. And I believe that we are poised to make steady progress on some of the most important issues of our times," he said.

Obama said no nation can meet the challenges of the 21st century on its own, which "only makes US-China dialogue more important."

The US side also gave unprecedented priority to the dialogue, the first of its kind under the Obama administration. Twelve officials at or above the ministerial level, including Secretary of State Hillary Clinton and Secretary of Treasury Timothy Geithner who are co-chairing the dialogue for the American side, were involved in the dialogue.

"Same boat" theory

It is widely noticed that Clinton has time and again preached the "same boat" theory while making important remarks on US-China relations on various occasions.

In a joint letter to The Wall Street Journal published on Monday, Clinton and Geithner stressed the importance of the dialogue, saying "few global problems can be solved by the US or China alone. And few can be solved without the US and China together."

"The strength of the global economy, the health of the global environment, the stability of fragile states and the solution to nonproliferation challenges turn in large measure on cooperation between the US and China," said the two key cabinet members in the letter.

Chinese Vice Premier Wang Qishan (2nd L), State Councilor Dai Bingguo (1st L), USSecretary of State Hillary Clinton (2nd R) and US. Treasury Secretary Timothy Geithner (1st R) pose for a photo before the opening of the China-US Strategic and Economic Dialogue (SED) in Washington, the United States, July 27, 2009. The China-US Strategic and Economic Dialogue (SED), the first of its kind between the world's biggest developing country and biggest developed country, opened here on Monday. [Zhang Yan/Xinhua]

"But having these strategic-level discussions with our Chinese counterparts will help build the trust and relationships to tackle the most vexing global challenges of today -- and of the coming generation," says the letter.

The top US diplomat and top financial official cited the Chinese aphorism "When you are in a common boat, you need to cross the river peacefully together" to express their hope of strengthening cooperation between the two countries. China has now become Washington's single biggest creditor, with 801.5 billion dollars in Treasury securities, according to the US Treasury Department.

Addressing the opening ceremony, Geithner echoed Clinton's "same boat" theory by speaking in Mandarin Chinese "Tong Zhou Gong Ji", the Chinese phrase for "the same boat" theory, and expressed hope that both sides could work together to tackle tough global issues.

Top concern for both countries

Observers here have noticed that both China and the United States are giving top priority to economic issues on their agenda.

In the joint letter to The Wall Street Journal, Clinton and Geithner said that "at the top of the list will be assuring recovery from the most serious global economic crisis in generations and assuring balanced and sustained global growth once recovery has taken hold."

The second and third priorities are "making progress on the interconnected issues of climate change, energy and the environment," and "finding complementary approaches to security and development challenges in the region and across the globe."