US President Donald Trump
© Leah Millis / ReutersUS President Donald Trump
US President Donald Trump has said that he will decide on potential actions against Syria within 24-48 hours in response to reports of an alleged chemical attack in Douma, East Ghouta.

Trump promised a swift response to the "heinous attack," saying that "this is about humanity and it can't be allowed to happen."

His statements echo earlier remarks by Defense Secretary James Mattis. When asked by a reporter if the US was considering military strikes against Syria, Mattis replied that he "would not rule out anything right now."

Comment: US Defense Secretary James Mattis has not ruled out the possibility of launching airstrikes against Syria in response to an alleged chemical attack in the militant-held town of Douma.
Speaking with reports on Monday, Mattis said he wouldn't "rule out anything right now" after being asked if the US was mulling strikes against Syrian President Bashar Assad.

"The first thing we have to look at is why chemical weapons are still being used at all. Russia was the framework guarantor of removing all the chemical weapons and so working with our allies and partners, from NATO to Qatar and elsewhere we are going to address this issue," he added.

On Sunday, Trump wrote on Twitter that there would be a "big price to pay" for the alleged attack.

Moscow says the accusations against Damascus serve as a baseless provocation. It has warned that any military action taken to 'respond' to the alleged incident would have "dire consequences." Trump used similar language after an alleged chemical attack was carried out in Idlib province last April. He later ordered a Tomahawk missile strike against a Syrian airbase in Homs.

The US State Department said in a statement released on Monday that victims of the alleged attack in Douma showed symptoms of exposure to a nerve agent, and called on Syria and Russia to open the area to international monitors.

Saturday's alleged chemical attack in Douma, Eastern Ghouta, comes as pro-government forces conclude an operation that has liberated nearly the entire region from Islamic militants. The alleged chemical incident was reported by pro-jihadist groups and it could not be confirmed by Red Crescent medics on the ground.Following the reports, two Israeli warplanes targeted a Syrian airbase in Homs on Sunday night, according to the Russian and Lebanese militaries.

Monday also marks John Bolton's first day as Trump's new national security advisor. Bolton, a former Bush-era ambassador to the UN, has been a vocal proponent of more US military involvement in the Middle East.