KELLY MCEVERS, HOST:

There are more terrible pictures from Syria today of wounded and dying children and adults in the province of Idlib. That's an area that's held by rebels. The Syrian Observatory for Human Rights, an opposition-leaning monitor, says at least 58 people were killed by chemical weapons and conventional bombs, and that death toll is expected to rise.

The White House is blaming the Syrian regime. NPR's Alison Meuse joins us now from Beirut. And Alison, tell us what happened in Idlib.

ALISON MEUSE, BYLINE: Well, earlier this morning, we had reports of multiple airstrikes on a town called Khan Sheikhoun in rebel-held northern territory. That monitor you mentioned said that in addition to people being killed by the bombs, dozens were killed by what appeared to be toxic substance. Now, activists published videos showing the purported victims, including many children, who didn't appear to have any outward physical wounds. Other videos showed survivors getting hosed down by rescuers and many struggling to breathe.

I reached an activist from a nearby town who drove to the scene today. He said there were so many victims they had to be sent to hospitals in other towns. So we still don't know the full extent of the death toll, but there could be well over 200 between the wounded and dead.

MCEVERS: White House Spokesperson Sean Spicer says that the chemical attack was a heinous action by Syrian President Bashar al-Assad. Opposition sources also blame him. What evidence points to the regime?

MEUSE: Well, we're not on the ground. I mean I'm in Beirut, but what we do know is this is an area dominated by hardline rebel factions and which regularly comes under attack by Syrian and Russian warplanes. The Syrian army has denied any use of chemical or toxic substances in this area, and Syria agreed to give up its chemical weapons stockpile back in 2013 under a U.S.- and Russia-brokered deal.

But in the years that followed, there have been persistent allegations of toxic gases being used. The U.N. and the Organization for the Prohibition of Chemical Weapons found that government forces had used toxic chemicals as weapons on three occasions in recent years. So there is a track record. Now, the U.N. and OPCW say they're very concerned about these latest allegations and are in the process of investigating.

MCEVERS: The U.S. and other Western powers have been urging that Assad be removed from power for years. Do you think there's any political will to do that now?

MEUSE: Well, the U.S. ambassador to the U.N., Nikki Haley, has called for a Security Council meeting tomorrow, but they've been talking like this for years. Now, I reached an analyst, Emile Hokayem, who pointed out that even when there was a big sarin gas attack in 2013 that killed hundreds of people in the Damascus suburbs, that didn't provoke a military response from the U.S.

EMILE HOKAYEM: I don't think this is going to be either a turning point or a moment where, you know, the Trump administration or someone else decides to do something about it. If anything, it's going to highlight the paucity of options and the divisions in the international community as the priority is understandably given to fighting ISIS in Raqqa.

MEUSE: And that's just it. The U.S. and other countries - say, Turkey and the Gulf States that long backed the opposition - have other priorities today - for the U.S., namely fighting ISIS. And Assad's key backers, Iran and Russia, have always been willing to go a step further militarily that the U.S. just isn't willing to go.

MCEVERS: NPR's Alison Meuse in Beirut, thank you very much.

MEUSE: Thanks so much, Kelly. Transcript provided by NPR, Copyright NPR.