The Obama administration fears that the beleaguered Syrian regime may unleash chemical weapons on rebels who are pressing their campaign closer to the capital of Damascus.
"I think there is no question that we remain very concerned, very concerned that as the opposition advances, in particular on Damascus, that the regime might very well consider the use of chemical weapons," Defense Secretary Leon Panetta said today.
"The intelligence that we have causes serious concerns that this is being considered," he said.
The regime of Syrian President Bashar al-Assad has moved to prepare some of its chemical weapons for use. U.S. officials reacted with alarm this weekend after U.S. intelligence uncovered Syrians moving components of sarin gas into bombs on or near Syrian airfields, a senior U.S. official said Wednesday.
Two U.S. officials said Wednesday it was still very unclear what the intent was behind the activity that caught their attention. There is nothing that suggests Assad ordered the chemicals be moved.
The heightened concern comes as Secretary of State Hillary Clinton imet today with U.N. Special Envoy Lakhdar Brahimi and Russian Foreign Minister Sergei Lavrov to discuss the options to end the conflict in Syria.
The idea behind the meeting in Dublin is that the three parties might be able to revive the political transition plan on Syria put forward in Geneva in July.
Before the meeting began Clinton said, "Events on the ground in Syria are accelerating, and we see that in many different ways. The pressure against the regime in and around Damascus seems to be increasing. We've made it very clear what our position is with respect to chemical weapons."
The Obama administration has said the use of chemical weapons would be a "red line."
The meeting last for 40 minutes and a senior State Department official said, "It was a constructive discussion focused on how to support a political transition in practical terms. The U.S. and Russia committed to support Special Envoy Brahimi's efforts in that regard. The next step will be a meeting in the next few days between Special Envoy Brahimi and senior officials from the United States and Russia to discuss the specifics of taking this work forward."
That plan by the so-called Action Group for Syria called for an immediate cessation of violence, the withdrawal of Syrian troops to their bases, access for humanitarian agencies and the establishment of a transitional governing body with officials from across the political spectrum.
It did not call on Assad to step down, which Russia has long rejected, and the plan never really went anywhere. Its main proponent was former U.N. Secretary General Kofi Annan who later resigned as special envoy to Syria and Brahimi was appointed to the post.
As the conflict reaches almost two years, there is speculation that Russia's stance may be softening. Russia is Syria's closest ally outside the Middle East and a shift in its support for Assad would likely spell the end of his rule.
Syria's current Deputy Foreign Minister Faisal Mekdad told Sky NewsWednesday that international intervention in Syria would be "dangerous for the whole region" and that it is "funny" to think that Syria could threaten a NATO country.
"In no way we can threaten a NATO country and these are just provocations and further support for the terrorist groups that are supported by the Turkish government and by many European countries," Mekdad said.
Mekdad also told Sky News that Assad will "never, ever" leave Syria and said "even if" Syria has chemical weapons it would not use them against its own people.
"We are saying if we have them we shall not use them against our people," Mekdad said.