With Congress divided over chemical weapons assessment in Syria, Republicans want the White House to act, but the latter remains cautious. For Senator McCain however, "It's pretty obvious that red line has been crossed."

Damascus (AsiaNews/Agencies) - US intelligence agencies believe "with varying degrees of confidence" that Syria has used chemical weapons against rebels. Yesterday, former presidential candidate John McCain said that the Syria crossed the red line set by President Barack Obama for intervention. Appealing to the country's sense of responsibility, the Republican senator said, "It's pretty obvious that red line has been crossed."

The international community has been monitoring the use of chemical weapons in Syria for months with the Syrian regime and rebels accusing each other over their use. Since March, a United Nations delegation has been waiting in Cyprus to visit the country to verify their respective charges.

American intelligence has known about the presence of chemical weapons in Syria for quite some time. However, it has remained cautious about its possible use in the conflict.

US Secretary of Defence Chuck Hagel recently stressed that the new intelligence assessment is not a sufficient basis for military intervention. However, he warned that the use of such weapons "violates every convention of warfare."

President Barack Obama, who said in Israel last month "that the use of chemical weapons is a game changer," is now under pressure from both US allies and domestically from Republicans and Democrats alike.

Backed by France, British PM David Cameron spoke of "growing evidence [. . .] of use of chemical weapons, probably by the regime."

Pro-democracy groups have called for a no-fly zone like the one established in Libya.

Yet, although a 'red line' has been drawn, nothing has been said about how a possible intervention in Syria could occur.

Some Gulf countries have already begun to arm the rebels, but despite pressure from Britain and France, Barack Obama is playing for time.

Anthony Cordesman, a military analyst at the Center for Strategic and International Studies, a Washington policy research group, said that "two small uses, if we can't tie it to Assad and to the regime, isn't really a red line," especially after the Bush experience in Iraq.

Meanwhile, Secretary of State John Kerry last week announced that the US is providing an additional US$ 123 million to the Syrian opposition, doubling so-called nonlethal aid.

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