The United States runs a "very real" risk of losing its top triple-A rating if nothing is done to reduce the ballooning deficit, an official said Friday after debt talks collapsed.

Republicans in the House of Representatives abruptly closed the door on acrimonious negotiations with President Barack Obama on raising the $14.3 trillion U.S. debt ceiling.

British forces have detained two British nationals in Afghanistan, authorities in London said Thursday, amid reports they were suspected of plotting against Britain or fighting with the Taliban.

"We can confirm that British forces have detained two individuals in Afghanistan who claim to be British nationals," the Ministry of Defense said in a statement.

Tibet's spiritual leader the Dalai Lama has insisted that he will guide the choice of his successor, saying China's plans to control the selection of the Buddhist leader were "ridiculous."

The Dalai Lama on Monday headed back to his home in exile in India after a nearly two-week visit to the United States. President Barack Obama welcomed him Saturday at the White House, leading China to lodge a protest.

General David Petraeus, the U.S. commander in Afghanistan and most celebrated military leader of his generation, stepped down on Monday after a checkered year at the helm of what is America's longest war.

At a ceremony in Kabul Petraeus passed the baton to John Allen, a former subordinate who made his name in Iraq by striking tribal alliances considered integral in reversing al-Qaida's momentum after years of appalling violence.

The Dalai Lama said Saturday that U.S. President Barack Obama shared "genuine concerns" about human rights in Tibet during a White House meeting held despite protests by China.

Obama is "president of the greatest democratic country, so naturally he is showing concern about basic human values, human rights, religious freedom," the Dalai Lama said after his meeting in response to a question from Agence France Presse.

Yemeni President Ali Abdullah Saleh, who has been receiving treatment for blast wounds in Saudi Arabia since early June, will return "soon," deputy information minister Abdo al-Janadi said Saturday.

"The president is in good health. He will return to Yemen soon, but is awaiting the decision of his doctors," Janadi told a news conference, without specifying a date for Saleh's return.

Astronauts aboard the International Space Station got a very long-distance call Friday from U.S. President Barack Obama, who joked that he thought he was dialing out for pizza.

Hot from giving a press conference at which he pushed Republicans to reach a deal on raising the U.S. debt ceiling, the American president took time out to chat with the 10 astronauts currently aboard the ISS.

Largest U.S. creditor China and Wall Street piled on pressure Thursday for President Barack Obama and his Republican foes to reach an elusive budget compromise and avert a ruinous early August default.

Cries of alarm over the stalemate's potential impact on the world economy grew louder as Obama and congressional leaders opened their fifth straight day of talks at the White House with long odds of a breakthrough.

The first American soldiers of about 10,000 due to leave Afghanistan this year have flown home, military officials said Friday, kicking off a gradual drawdown due to be completed in 2014.

U.S. President Barack Obama in June announced that 33,000 American troops would leave Afghanistan by the end of next summer, leaving behind 65,000 and effectively ending a military surge ordered into the country late 2009.

The United States said Thursday that it disagreed with the Arab League after it said it would submit a request for recognition of a Palestinian state to the United Nations.

"We do not believe attempts to resolve final status issues in international bodies like the United Nations are able to bring about the enduring peace, which both the parties and the United States seek," the State Department said in a written statement.