US President Barack Obama has formally asked Congress to authorise military action against Syria over alleged chemical weapons attacks.
He said any operation would be limited, ruling out a ground invasion. Congress is to reconvene on 9 September.
This comes after Washington claimed it had evidence that 1,429 people were killed in chemical attacks by the Syrian army on 21 August.
The Syrian government gave no immediate reaction to Mr Obama's announcement.
Damascus had earlier condemned the US allegations and blamed the rebels for the attacks.
President Obama was elected to end America's wars, and in reaction to the fallout of the invasion of Iraq. He knows, as he frankly admitted, that Americans are "weary of war". Many of his own supporters want him to focus on what he calls "nation-building at home".
But he is trapped within his own red lines and perhaps the need to send a signal to Iran and North Korea. White House sources say the British vote shows the dangers of allowing a debate - but it also removed a key ally and so, ironically, made support at home even more vital.
It also increased the demands from Congress itself to have a say. A recent poll indicated 80% of Americans thought Congress should vote before any military action. Some will say the decision shows President Obama is weak. It certainly shows the weakness of his position - he wants to take action that isn't popular and home or abroad.
But it is sensible to make sure the responsibility for unpopular action is shared with other politicians, and canny for domestic reasons to keep a very sour Congress sweet. Some might even argue that, in a democracy, it is the right thing to do.
In other developments:
- UN inspectors who have been investigating the attacks have arrived in the Netherlands with samples from site visits. They say the testing could take up to three weeks
- Foreign ministers from the Arab League are to discuss Syria at a meeting in Cairo, amid deep splits on the issue
- Opposition members in France - a key US ally - have urged President Francois Hollande to seek a formal vote before joining Washington in any military operation in Syria
'Critical debate'
In a statement at the White House on Saturday, President Obama said that he decided that the US "should take action against Syrian regime targets".
As commander-in-chief, Mr Obama has the constitutional authority to launch strikes without the backing of Congress - the Senate and the House of Representatives.
However, he said it was important to have the debate.
"I've long believed that our power is rooted not just in our military might, but in our example as a government of the people, by the people, and for the people.
"And that's why I've made a second decision: I will seek authorisation for the use of force from the American people's representatives in Congress," he said.
Later on Saturday, Mr Obama sent a "draft legislation" to the speaker of the House of Representatives and the president of the Senate.
Senior White House officials told the BBC's Katty Kay that Mr Obama's decision to seek congressional approval was made by the president on Friday afternoon. It had not been planned until then.
The officials added that they believed they would get congressional approval, although they were aware of the risks, our correspondent adds.
Senate Majority Leader Harry Reid, a Democrat, said the chamber "will engage in this critical debate right away", pledging the vote on the proposal would take place no later than the week of 9 September.
Senate Minority Leader Mitch McConnell, who is a Republican, also welcomed the move, saying the president's role as commander-in-chief was "always strengthened when he enjoys the expressed support of the Congress".
But Republican Senators John McCain and Lindsey Graham, who have been pushing for US intervention in Syria, warned against limited strikes which would not change the balance of the conflict, calling the prospect "an inadequate response".
In the House of Representatives, Republican Speaker John Boehner and other party members praised Mr Obama's decision "in response to serious, substantive questions being raised".
Discussion of the issue is expected to kick off on Tuesday with a hearing in the Senate Foreign Relations Committee.
The BBC's Katy Watson in Washington says that if Mr Obama is to intervene militarily, he wants the people - and politicians - on his side.
But what is unclear is what action he would take if Congress votes against involvement, our correspondent says.
'Utter nonsense'
The president's decision to turn to Congress was seen as a direct reaction to the UK government's defeat in Parliament on supporting any military action in Syria if it were backed by evidence from UN inspectors.
After the White House announcement, UK Prime Minister David Cameron tweeted: "I understand and support Barack Obama's position".
Mr Obama did not speak to Mr Cameron before his statement but did call President Hollande, the White House said.
France has also backed military action, and its parliament is due to reconvene next week.
Mr Hollande will wait for discussions in the US Congress and French parliament before making a decision on military intervention, a French official told the Associated Press.
Earlier on Saturday, Russian President Vladimir Putin challenged the US to present to the UN evidence that Syria had attacked rebels with chemical weapons.
Mr Putin said it would be "utter nonsense" for Syria's government to provoke opponents with such attacks.
Russia - a key ally of Syria - has previously warned that "any unilateral military action bypassing the UN Security Council" would be a "direct violation of international law".
Moscow, along with China, has vetoed two previous draft resolutions on Syria.
The BBC's Jeremy Bowen in Damascus says people there are worried and are making preparations.
They did not know what Mr Obama meant by a limited attack and what consequences it would have, he adds.
The main findings of an unclassified US intelligence assessment on the Damascus attacks were that:
- the attacks killed 1,429 people, including 426 children
- Syrian military chemical weapons personnel were operating in the area in the three days before the attack
- Satellite evidence shows rockets launched from government-held areas 90 minutes before the first report of chemical attack
- 100 videos attributed to the attack show symptoms consistent with exposure to a nerve agent
- Communications were intercepted involving a senior Damascus official who "confirmed chemical weapons were used" and was concerned about UN inspectors obtaining evidence
Syrian President Bashar al-Assad has said his country will defend itself against any Western "aggression".
Forces which could be used against Syria:
• Four US destroyers - USS Gravely, USS Ramage, USS Barry and USS Mahan - are in the eastern Mediterranean, equipped with cruise missiles. The missiles can also be fired from submarines, but the US Navy does not reveal their locations
• Airbases at Incirlik and Izmir in Turkey, and in Jordan, could be used to carry out strikes
• Two aircraft carriers - USS Nimitz and USS Harry S Truman are in the wider region
• French aircraft carrier Charles de Gaulle is currently in Toulon in the western Mediterranean
• French Rafale and Mirage aircraft can also operate from Al-Dhahra airbase in the UAE
Đăng ký: Tieng Anh Vui