The United States has postponed a meeting with Russian officials scheduled for later this week to discuss the situation in Syria, as Washington weighs its response to allegations that Syrian forces used chemical weapons last week.
The talks Thursday were due to be the latest in the U.S.-Russian bid to find a political solution to the crisis.
A senior State Department official said late Monday the delay is in light of the "ongoing consultations" on how to respond to reports of chemical weapons use in Syria.
A White House spokesman said Monday there is "very little doubt" the Syrian government used chemical weapons.
Russia, a Syrian ally, has dismissed the allegations, saying the United States and other Western nations do not have proof of such an attack.
The U.S.-Russian effort to bring together the Syrian government and the opposition for peace talks has yet to result in negotiations. The State Department official says the U.S. remains committed to the process and will reschedule the planned talks with Russia.
U.S. Secretary of State John Kerry said Monday the use of chemical weapons in Syria is a "moral obscenity." He said President Barack Obama believes there must be accountability for those who would use what he called such "heinous weapons."
Mr. Obama is evaluating potential options, but has not decided on any response.
Kerry said that in the days following the reports of the chemical weapons attack, the Syrian government refused access to the site, and instead shelled the area. He said "that is not the behavior of a government that has nothing to hide."
There has been mounting pressure on the United States and other countries to address Syria's two-year conflict, following allegations last week that chemical weapons were used outside of Damascus, killing hundreds of people.
President Obama said last year that chemical weapons use in Syria would cross a "red line,'' and likely would change his calculation in deciding on a U.S. response. However, the president took little action after reports earlier this year that chemical weapons were used on a small scale in Syria.
Earlier Monday, U.S. Defense Secretary Chuck Hagel said any action on Syria will be taken "in concert with the international community and within the framework of legal justification." He made the comment on a visit to Indonesia.
Some U.S. lawmakers, including Mr. Obama's opponent in the 2008 presidential election, Senator John McCain, have called for limited strikes against Syrian military targets.