The meeting between Clinton and Foreign Minister Sergey Lavrov Thursday, hosted by the U.N.-Arab League special envoy Lakhdar Brahimi, will occur in the sidelines of a meeting on European security, The New York Times reported.
"Secretary Clinton has accepted an invitation by U.N. Special Envoy Brahimi for a trilateral meeting on Syria this afternoon with Mr. Brahimi and Russian Foreign Minister Lavrov," a senior State Department official said in a terse announcement Thursday morning.
Meanwhile, the German Cabinet agreed to send Patriot air defense missiles and troops to Turkey to help protect the NATO ally from possible Syrian attacks, Voice of America reported. The deployment also must be approved by the German Parliament, which is expected to endorse the measure.
The Netherlands and the United States also are expected to send Patriot missiles to Turkey.
NATO earlier this week approved Turkey's request, made after Syrian missiles landed in Turkey in October. The military alliance has emphasized the system is strictly defensive and doesn't signal an intention of intervening in the Syria conflict.
Clinton, Lavrov and former U.N. Secretary-General Kofi Annan, the U.N. envoy on the Syria crisis at the time, had discussions about Syria in June, but they did not produce an agreement on forming a transitional government or the removal of Bashar Assad as president.
Now, however, a string of tactical victories indicate rebel forces seem to be gaining on the ground and some Russian officials reportedly don't believe Assad can remain in power and so are interested in seeking an accord for a transition, the Times said.
U.S. officials told NBC News Syria was poised to use the deadly sarin nerve agent against its own people Thursday after loading precursor chemicals into aerial bombs. The bombs could be dropped on Syrians in "tactical bombings" from dozens of fighter-bombers.
The regime's military awaited orders from Assad, said the network, whose report was corroborated by Fox News Channel.
A senior U.S. official told Fox News Syria had 60 days to use the bombs until the chemical mixture expired. At that point the bombs would have to be destroyed, the official said.
Clinton and Lavrov are in Dublin for a meeting of the Organization for Security and Economic Cooperation in Europe that began Thursday.
Clinton, during a NATO meeting in Brussels Wednesday, reiterated a U.S. warning to Assad not to use chemical weapons, saying the alliance would consider such use crossing "a red line" that would lead to serious consequences. U.S. President Obama issued a similar warning Monday.
Clinton told reporters Wednesday the Assad regime was on the brink of collapse.
"It is just a question of how many people have to die before that occurs," she said.
The entire NATO military alliance was therefore concerned "an increasingly desperate Assad regime might turn to chemical weapons, or might lose control of them to one of the many groups that are now operating within Syria," Clinton said.
U.S. officials have intimated U.S. relations with the opposition could be enhanced, possibly even a formal recognition, if the coalition makes progress in developing its political structure by the time the Friends of Syria meets in Morocco later this month.
"Now that there is a new opposition formed, we are going to be doing what we can to support that opposition," Clinton said in Belgium Wednesday. "We will explore with like-minded countries what we can do to" end this conflict.
Elsewhere, the United States is progressing in designating one Syrian opposition group, al-Nusra Front, as an international terrorist organization, officials told the Times. Experts see the group as being affiliated with al-Qaida. The Times said the designation would align with a surfacing strategy toward the opposition and would seek to isolate radical elements of anti-Assad organizations.