President Donald Trump lashed out Sunday at Russian President Vladimir Putin and Iran for supporting Syrian President Bashar Assad following a reported government chemical attack in Syria that left dozens dead.

“President Putin, Russia and Iran are responsible for backing Animal Assad,” Trump tweeted. “Another humanitarian disaster for no reason whatsoever. SICK!”

Many dead, including women and children, in mindless CHEMICAL attack in Syria. Area of atrocity is in lockdown and encircled by Syrian Army, making it completely inaccessible to outside world. President Putin, Russia and Iran are responsible for backing Animal Assad. Big price... — Donald J. Trump (@realDonaldTrump) April 8, 2018

....to pay. Open area immediately for medical help and verification. Another humanitarian disaster for no reason whatsoever. SICK! — Donald J. Trump (@realDonaldTrump) April 8, 2018

Trump, often reluctant to criticize Putin, suggested there would be a “big price to pay,” though it’s unclear if he was referring to the Russian and Iranian governments for backing the oppressive Syrian leader or the Syrian government for allegedly carrying out the attack.

A chemical attack in the rebel-held Syrian town of eastern Ghouta on Saturday left at least 49 people dead, including over a dozen children, according to the Syrian American Medical Society, a medical relief organization. Aid groups blamed Assad’s government for the attack, though the Russian-backed regime denied it was behind it.

Trump ordered a military strike against the Assad regime in April 2017 in response to a brutal chemical attack that killed over 70 civilians in the rebel-held town of Khan Sheikhoun. Trump has recently said that he would like U.S. military forces to pull out of Syria.

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The State Department said Sunday it was working to confirm if the Syrian government was behind the suspected chemical attack.

“These reports, if confirmed, are horrifying and demand an immediate response by the international community,” State Department spokeswoman Heather Nauert said in a statement.

Trump also blamed former President Barack Obama on Sunday for failing to end the bloody conflict in Syria “long ago.” He tweeted that Obama should have followed through on his 2012 pledge to intervene militarily if the Syrian government used chemical weapons against its people.

If President Obama had crossed his stated Red Line In The Sand, the Syrian disaster would have ended long ago! Animal Assad would have been history! — Donald J. Trump (@realDonaldTrump) April 8, 2018

The U.N. Security Council will hold an emergency meeting Monday to address the suspected chemical attack in Syria, U.N. Ambassador Nikki Haley announced Sunday.

In a statement Sunday, Sen. John McCain (R-Ariz.), chairman of the Senate Armed Services Committee, called on Trump to respond “decisively” to the attack.

“President Trump was quick to call out Assad today, along with the Russian and Iranian governments, on Twitter,” McCain said. “The question now is whether he will do anything about it. The president responded decisively when Assad used chemical weapons last year. He should do so again, and demonstrate that Assad will pay a price for his war crimes.”

This article has been updated with information about the U.N. Security Council and McCain’s comments.

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This article originally appeared on HuffPost.