Syria's foreign minister says his country will defend itself using "all means available" in case of a U.S. strike.

Walid Al-Moualem, Minister of Foreign Affairs for Syria (Mario Tama/Getty Images)

Walid al-Moallem says Syria has two choices, either to surrender or fight back, and it will choose the latter.

He declined to elaborate or say to what specific means he was referring.

Al-Moallem spoke at a press conference in the Syrian capital today amid growing international support for military action against Syria in response to what U.S. Secretary of State John Kerry said was "undeniable" evidence of a large-scale chemical attack likely launched by Damascus.

Al-Moallem challenged anyone accusing the Syrian regime of using chemical weapons to provide proof.

Meanwhile, Prime Minister David Cameron has recalled Parliament for an urgent discussion on a possible military response to the alleged chemical attack in Syria. Cameron says the crisis session will be held Thursday, when Parliament would traditionally be on its summer recess.

He said Tuesday that there would be a clear government motion and vote on the British response to a chemical weapons attack in Syria.

Legislators had been urging Cameron to consult Parliament before any possible action against Syria.

Concern for Syria prompts UN chemical guidelines

A spokesman for the World Health Organization says it has rushed out new guidelines for treating victims of chemical warfare agents like those purportedly used in the Aug. 21 attack in the suburbs of Damascus.

Spokesman Glenn Thomas says that the specific guidelines were being prepared before the U.N.'s chemical inspection team, which includes three WHO staffers, began working in Syria this week.

But he told reporters today in Geneva that "we did rush this out" because of the concern over Syria and the document would "evolve as we have a better understanding of the risks."

U.N. spokeswoman Alessandra Vellucci says the inspection team might need longer than the planned 14 days to complete its work and its priority now is to determine what happened in the Aug. 21 attack.

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