The United States is formulating a military plan to punish Syrian President Bashar al-Assad's government, convinced that the regime is responsible for a recent chemical attack against Syrian civilians.

"We have concluded that the Syrian government in fact carried these out," U.S. President Obama said during an interview with PBS NewsHour. "And if that's so, then there need to be international consequences."

But a strike on Syria would need unanimous Security Council approval, the United Nations announced at a press conference, Wednesday.

While asserting that the recent chemical attack in the Ghouta suburb of Damascus was "outrageous...unacceptable," UN representative Lakhdar Brahimi said that the international community must develop the political will to look for a solution.

Earlier Wednesday, the five permanent members of the Security Council failed to reach an agreement on a draft resolution from the British seeking authorization for the use of force.

Russia, as expected, objected to international intervention, saying the Security Council must wait until chemical weapons inspectors finish their investigations before any "premature" decisions on military force are made.

U.S. officials have said they would take action against the Syrian government even without the backing of allies or the UN because diplomatic paralysis must not prevent a response to the chemical attacks.

The Obama administration is planning a "tailored, limited" strike, not a protracted engagement like Iraq, in response to the chemical attacks they assert have been carried out by the Syrian regime.

"If we are saying in a clear and decisive but very limited way, we send a shot across the bow saying, 'Stop doing this,' this can have a positive impact on our national security over the long term," Obama told PBS Newshour.

Despite the administration's assertions that it would press forward without the UN, momentum for international military action appeared to slow, as Obama and U.K. Prime Minister David Cameron brief their respective governments on the case against Assad.

Regime continues to deny responsibility for attacks

Syrian Ambassador to the United Nations Bashar Ja'afari again rejected "baseless accusations" of chemical weapons use by his country's government. He told reporters Wednesday that he has information about an alleged rebel attack in which deadly sarin gas was used against Assad's troops.

Ja'afari said he brought a letter from the regime requesting that UN weapons inspectors "immediately" turn their attention towards investigating "three heinous incidents" of alleged chemical attacks against government forces on August 22, 23 and 24. The regime has asked the UN inspectors to extend their stay in Syria and investigate their claims. The request could delay U.S. military action.

"Dozens of Syrian soldiers are currently treated in the Syrian hospitals due to this use of chemical agents by the terrorist armed groups operating in the countryside of Damascus," said Ja'afari.

Asked how he believes rebel fighters might have obtained chemical weapons, he said he believes ingredients for the production of toxic agents were smuggled in from outside Syria.

Investigations underway

UN Secretary General Ban Ki-moon said the special team tasked with investigating possible chemical warfare in Damascus will need at least four more days to collect the evidence they need.

A UN chemical weapons expert wearing a gas mask carries samples from one of the sites of an alleged chemical weapons attack in the Ain Tarma neighbourhood of Damascus on Wednesday. (Mohamed Abdullah/Reuters)

The team's first field testing began in the western suburb of Moadamiyeh on Monday. The journey was delayed by sniper fire, though the team was unharmed. On Wednesday, the UN's convoy of seven SUVs again left a hotel in central Damascus to resume inspections.

According to anti-regime activists, the inspectors made their way this time to the Damascus suburb of Eastern Gout, which was affected by the alleged chemical attack.

UN inspectors have not accused rebel fighters or government troops of using chemical weapons.

Canada says firm response is necessary

Canadian Foreign Affairs Minister John Baird has called the alleged chemical attack an "outrage" and Prime Minister Stephen Harper is conferring closely with Obama as the Syrian situation escalates.

After meeting with the head of the Syrian National Council president George Sabra in Ottawa, Baird said that a "firm international response is needed" to last week's attacks. Baird said it's not clear yet how Canada could contribute to a possible military intervention.

On Tuesday, Baird met with NDP Leader Thomas Mulcair and Liberal Leader Justin Trudeau to brief them on developments in Damascus.

Speaking to reporters Wednesday, Trudeau said he would be happy to see Parliament recalled in order to discuss Canada's possible role in Syria.

"All the parliamentarians are united in our horror and our desire to help," he said. "Humanitarian aid, greater help in terms of refugees — these are things that Canada can do and the Canadians are united and wanting to do."

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