The U.S. secretaries of state and defense are to appear before a Senate panel as President Barack Obama seeks to secure congressional backing for his plans to respond with military action to last month's alleged chemical-weapons attack in Syria.
Secretary of State John Kerry and Defense Secretary Chuck Hagel are due to testify before the Senate Foreign Relations Committee.
Obama said on August 31 that he wanted the approval of the U.S. Congress for "limited" and "narrow" military action in response to the August 21 poison-gas attack near Damascus that the United States says was carried out by Syrian President Bashar al-Assad's regime.
France on September 2 released an intelligence report that also blamed Assad's regime for last month's attack.
Assad has warned that military strikes against Syria risk setting off a wider conflict in the Middle East.
A senior State Department official said Kerry will argue on September 3 that failing to act in Syria "unravels the deterrent impact" of international norms banning chemical-weapons use.
Kerry is also expected to warn that inaction would endanger Washington's friends and partners in the region, while emboldening Assad and his key allies, Lebanon's Shi'ite militant group Hizballah and Iran.
France Blames Assad Regime
France has said the alleged chemical attack near Damascus last month could have only been carried out by the Syrian government.
A French intelligence report said the assault on August 21 involved a "massive use of chemical agents."
It said that at least 281 deaths can be attributed to the attack.
The report was presented to parliament on September 2 by Prime Minister Jean-Marc Ayrault, who said, however, that France would take action only as part of an international coalition.
"There is no question of France acting alone. The president of the republic is working on persuading and bringing together a coalition as quickly as possible," Ayrault said.
"France has to get on board with this objective because France defends the principle of respecting international law."
France has emerged as the main U.S. ally in the Syria crisis after the British Parliament last week rejected involvement in any military action.
Russia, which along with China has blocked UN Security Council resolutions against Assad, said on September 2 it remained totally unconvinced the attack was carried out by Assad's forces.
China has warned of the risks of unilateral military action, with Chinese Foreign Ministry spokesman Hong Lei saying on September 3.
"China supports the United Nations conducting an independent, fair, objective, and professional investigation," Hong said.
"What actions the international community should take next should be determined by the results of the investigation, which should clarify whether or not someone used chemical weapons in Syria, and who used the chemical weapons. The results should be the premise and precondition for any action taken by the international community for the next step."
McCain Urges Action
In Washington, Senator John McCain (Republican-Arizona) told reporters at the White House that Obama must make a strong case for attacking Assad's Syria if he wanted to win congressional backing for the operation.
He also warned of "catastrophic" consequences if Congress voted "no" to attacking Syria.
"If the Congress were to reject a resolution like this after the president of the United States has already committed to action, the consequences would be catastrophic in that the credibility of this country with friends and adversaries alike would be shredded and it would be not only have implications for this presidency but for future presidencies as well." McCain said after talks on September 2 at the White House with Obama.
Obama has put off any intervention until Congress, which is in recess until September 9, has a chance to vote on the matter.
The Syrian government has repeatedly denied using chemical weapons.
In an interview published on September 2 in the French daily "Le Figaro", Assad said the Middle East was a powder keg and a Western attack on Syria could push the entire region into chaos.
He also said France would face "repercussions" if it took part in a military action.
NATO Chief: 'Firm' Response
At a news conference in Brussels earlier on September 2, NATO Secretary-General Anders Fogh Rasmussen called for a "firm" response to the use of chemical weapons in Syria.
Rasmussen added that any military action "would be very short, sharp, tailored."
"It would send a very, I would say, dangerous signal to dictators all over the world if we stand idle by and don't react," he said.
"The question is how to react and when to react and in democracies you have to respect and accept discussions and democratic procedures but it's my firm position that the international community should react in such a situation."
On September 1, U.S. Secretary of State Kerry said the United States had evidence that sarin gas was used in the attack. Kerry said the evidence had been presented to Moscow.
But Russian Foreign Minister Sergei Lavrov said a day later that the evidence left "serious doubts:"
"This is obviously a case of what we call 'double standards.' It is a clear case of personalities -- when a personal dislike toward an authoritarian leader leads to the idea that he must be overthrown by any means," Lavrov said.
The Chinese Foreign Ministry on September 2 also said the U.S. evidence had been presented to Beijing but cautioned against "rushing to prejudge" the evidence before UN inspectors issue their report.
UN inspectors are currently analyzing samples taken from the site of the alleged chemical attack.
UN: 2 Million Refugees
Meanwhile, the United Nations announced on September 3 that more than 2 million refugees have now fled Syria's civil war.
The UN refugee agency said the number of refugees had risen nearly 10 times over the past 12 months.
The UN High Commissioner for Refugees (UNHCR), Antonio Guterres, said "Syria has become the great tragedy of this century."
According to the UNHCR, almost 5,000 people take refuge in Syria's neighbors every day. It said the number of people displaced inside Syria was holding steady at around 4.25 million.
Ministers from Iraq, Jordan, Lebanon, and Turkey -- the four main hosts of Syrian refugees -- were due to meet officials from the agency in Geneva on September 4 to work out ways to raise more international aid.
With reporting by AP, dpa, Reuters, and AFP