The United Nations Security Council is currently meeting to discuss a resolution drafted by the US on the latest apparent chemical weapons attack in Syria, as inspectors from the international chemical weapons watchdog prepare to head into the country, NPR reported.
Meanwhile, President Trump is weighing a possible military response. Last night, he said "nothing is off the table" and has vowed to respond "forcefully."
Trump has now cancelled this week's planned trip to Latin America "to oversee the American response to Syria and to monitor developments around the world," according to White House press secretary Sarah Sanders.
In the attack over the weekend in Douma, a rebel-held area in the Damascus suburbs, pro-opposition rescue workers and doctors have told NPR's Ruth Sherlockthat at least 42 people died. That's equal to the number of fatalities reported by the Britain-based Syrian Observatory for Human Rights.
The Organisation for the Prohibition of Chemical Weapons said the Syrian government and its Russian allies invited it to send in a fact-finding mission. The watchdog group has a mandate to "establish facts surrounding the allegations of the use of toxic chemicals, reportedly chlorine, for hostile purposes in the Syrian Arab Republic."
The US-drafted resolution is expected to be considered this afternoon by Security Council members.
As NPR's Michele Kelemen reports, the resolution "would condemn the latest reports of a chemical attack and demand access to the scene in Douma. ... It would also create a new investigative mechanism to look into chemical weapons attacks in Syria and determine who is responsible."
Russia has previously voted to block a resolution that would give U.N. investigators a wider mandate on chemical weapons in Syria, Michele added. Today, she says, "if Russia vetoes, that could set the stage for U.S. military action in Syria."
It's not clear how the OPCW inspection in Syria would impact the timing of potential U.S. military action.
As NPR reported, Syria accused Israel on Monday of carrying out a raid on the Tiyas air base in central Syria in a pre-dawn raid.
Last year, the US carried out airstrikes against an airfield outside Homs after the Syrian regime was found to use chemical weapons.
Military action now would likely look similar, according to NPR's Pentagon correspondent Tom Bowman. "It could be wider airstrikes, more locations, command and control centers and so forth, to send the message," he reported.
On Monday, Trump indicated that the administration would be making "some major decisions over the next 24 to 48 hours."
French President Emmanuel Macron has indicated that he supports a "strong, joint response" to the reported chemical attack. And the White House says that in a call between Trump and UK Prime Minister Theresa May, the leaders "agreed not to allow the use of chemical weapons to continue."