WASHINGTON -- Edging toward a retaliatory strike, the Obama administration bluntly accused the Syrian government of Bashar Assad on Friday of launching a chemical weapons attack that killed at least 1,429 people -- far more than previous estimates -- including more than 400 children.

"Some cite the risk of doing things" in response, Secretary of State John Kerry said in a speech that acknowledged that Americans at home and U.S. allies abroad are weary of war. "But we need to ask what is the risk of doing nothing."

Halfway around the world, U.N. personnel carried out a fourth day of inspection as they sought to determine precisely what happened in the attack last week. Videotapes said to be taken at the scene show victims writhing in pain, twitching and exhibiting other symptoms associated with exposure to nerve agents. The international contingent arranged to depart Syria on Saturday and head to laboratories in Europe with the samples they have collected.

Residents of Damascus stocked up on food and other necessities in anticipation of strikes, although no signs of panic or shortages were evident.

"We got used to the sound of shelling" after three years of civil war, said Kheireddine Nahleh, a 53-year-old government employee. "Death is the same, be it with a mortar or with an American missile. I'm not afraid."

President Barack Obama met with his national security aides at the White House as aides insisted he has not yet made a decision to attack military facilities belonging to the Syrian government.

Even so, the administration did nothing to discourage the predictions that he would -- and soon.

"Our approach is to continue to find an international coalition that will act together," said Defence Secretary Chuck Hagel, on a trip to the Philippines.

U.S. warships were in place in the Mediterranean Sea armed with cruise missiles, long a first-line weapon of choice for presidents because they can find a target hundreds of miles distant without need of air cover or troops on the ground.

White House officials previewed the intelligence findings Thursday night in a telephone briefing for senior members of Congress.

The Assad government has accused rebels of carrying out the attacks.

The looming confrontation is the latest outgrowth of a civil war in which Assad has tenaciously -- and brutally -- clung to power. An estimated 100,000 civilians have been killed in more than two years, many of them as a result of attacks by the Syrian government on its own citizens.

Obama has long been wary of U.S. military involvement in the struggle, as he has been with turbulent events elsewhere during the so-called Arab Spring. In this case, reluctance stems in part from a recognition that while Assad has ties to Iran and the terrorist group Hezbollah, the rebels seeking to topple him have connections with al-Qaida terrorist groups.

Still, he declared more than a year ago that the use of chemical weapons would amount to a "red line" that Assad should not cross. And Obama approved the shipment of small weapons and ammunition to the Syrian rebels after an earlier reported chemical weapons attack, although there is little sign that the equipment has arrived.

With memories of the long Iraq war still fresh, the political cross-currents have been intense both domestically and overseas.

Dozens of lawmakers, most of them Republican, have signed a letter saying Obama should not take military action without congressional approval, and top leaders of both political parties are urging the president to consult more closely with Congress before giving an order to launch hostilities.

Despite the urgings, there has been little or no discussion about calling Congress back into session to debate the issue. Lawmakers have been on a summer break for nearly a month, and are not due to return to the Capitol until Sept. 9.

Obama's efforts to put together an international coalition to support military action have been more down than up.

French President Francois Hollande has endorsed punitive strikes, and told the newspaper Le Monde that the "chemical massacre of Damascus cannot and must not remain unpunished."

But British Prime Minister David Cameron's attempt to win a vote of approval in Parliament for military action ended in ignominious defeat on Thursday. American attempts to secure backing at the United Nations have been blocked by Russia, long an ally of Syria.

United Nations Secretary General Ban ki-Moon has urged a delay in any military action until the inspectors can present their findings to U.N. member states and the Security Council.

Ganley reported from Paris. Angela Charlton in Paris, Zeina Karam in Beirut and Albert Aji in Damascus, Syria, contributed to this report.