The relationship between the two countries may deteriorate more if Mr. Obama meets, as he is expected to, with the Tibetan spiritual leader, the Dalai Lama. Mr. Obama put off meeting with the Dalai Lama last year to avoid angering Beijing before his visit to China in November, a decision that received strong criticism from human rights activists.

Gen. James L. Jones, the national security adviser, said Friday that the announcement should not “come as a surprise to our Chinese friends,” adding that the Obama administration was “bent on a new relationship with China that goes beyond arms sales to Taiwan.” Speaking at the Center for Strategic and International Studies, General Jones sought to play down the escalating tensions between the United States and China.

Those tensions have been on full display since Mr. Obama traveled to Beijing in November. While Mr. Obama and Mr. Hu promised to conduct regular exchanges and to work together on a number of issues, they did not reach an agreement on how to move forward on Western efforts to rein in Iran’s nuclear ambitions. Obama administration officials now say that they view China, not Russia, as the main stumbling block on efforts to get a Security Council resolution that would impose additional sanctions on Iran.

A month after Mr. Obama went to Beijing, China blocked his efforts to reach a meaningful climate change agreement in Copenhagen. China announced this month that it had tested the country’s first land-based missile defense system, a test that Chinese and Western analysts said was timed to convey Beijing’s annoyance over the expected American arms sales to Taiwan. Throughout January, Chinese state news media have produced a torrent of articles condemning the expected sale.

China views Taiwan as a breakaway province, separated since the civil war of the 1940s, and sees arms sales as interference in an internal matter. The American relationship with Taiwan is one of the most delicate diplomatic issues between Beijing and Washington.

The deal announced Friday is the second big arms sale to Taiwan in two years. When the Pentagon announced in October 2008, under the Bush administration, that it was selling Taiwan $6.6 billion worth of weapons, China froze military ties with the United States and did not resume the contacts until after Secretary of State Hillary Rodham Clinton visited Beijing last February.

On Wednesday, the Pentagon spokesman, Geoff Morrell, urged China not to take that tack again. Responding to a question from a reporter before the sale was announced, Mr. Morrell said that “this relationship is too important to go through the fits and starts that we have over the years, where every little bump in the road results in a breaking of communication and a suspension of dialogue.”

Defense Secretary Robert M. Gates and Adm. Michael Mullen, the chairman of the Joint Chiefs of Staff, are both expected to travel to Beijing this year for high-level talks. Administration officials said Friday that they hoped China did not retract those two invitations.