The White House on Tuesday reacted to what appears to be Syria’s worst chemical attack in years by blaming former President Barack Obama.

“Today’s chemical attack in Syria against innocent people, including women and children, is reprehensible and cannot be ignored by the civilized world,” White House press secretary Sean Spicer said in a prepared statement at a news conference Tuesday morning, which was released by the administration later that day. “These heinous actions by the Bashar al-Assad regime are a consequence of the past administration’s weakness and irresolution.”

“President Obama said in 2012 he would establish a red line against the use of chemical weapons and then did nothing,” the White House said. “The United States stands with our allies across the globe to condemn this intolerable act.”

Secretary of State Rex Tillerson today ignored a question when asked for comment about the Syria chemical attack pic.twitter.com/DVVGlWkK9y — Bradd Jaffy (@BraddJaffy) April 4, 2017

Tuesday’s attack left scores dead in the town of Khan Sheikhoun in Idlib province. According to medical relief organization UOSSM, at least 100 people were killed and 400 others were injured. It was the worst such attack since August 2013, when dozens of civilians were killed in an attack with chemical weapons in the eastern Ghouta region of Syria.

While the White House on Tuesday was quick to condemn Obama for not acting more decisively against the Syrian regime, Donald Trump had said in the wake of the tragedy in eastern Ghouta that he strongly opposed intervention in Syria. “What I am saying is stay out of Syria,” Trump said on Twitter at the time.

If the U.S. attacks Syria and hits the wrong targets, killing civilians, there will be worldwide hell to pay. Stay away and fix broken U.S. — Donald J. Trump (@realDonaldTrump) September 3, 2013

Syria has repeatedly been under investigation for targeting civilians and opposition forces with chemical weapons. The Syrian government agreed in 2013 to a U.S.-Russian brokered deal to get rid of its chemical weapons stockpile. But international organizations, including Human Rights Watch, have warned several times since 2013 of new attacks using chemical weapons.

Tuesday’s victims had symptoms that often result from chemical attacks, such as foaming at the mouth. Many of the victims were were women and children, as well as people being treated at a hospital.

Secretary of State Rex Tillerson on Tuesday morning blatantly ignored questions from reporters about the attack. But Tuesday afternoon, Tillerson called on Russia and Iran to prevent the Assad regime from launching chemical weapon attacks. “While we continue to monitor the situation, it is clear that this is how Bashar al-Assad operates,” Tillerson said in a statement. “Those who defend and support him, including Russia and Iran, should have no illusions about Assad and his intentions.”

U.S. allies, including British Prime Minister Theresa May, sharply criticized the Syrian government over the attack. May called for an investigation into the incident and said, “If proven, this will be further evidence of the barbarism of the Syrian regime.”

Israeli Prime Minister Benjamin Netanyahu said the international community should work “to fully and finally remove these horrible weapons from Syria.”

There's no, none, no excuse whatsoever for the deliberate attacks on civilians and on children > — Benjamin Netanyahu (@netanyahu) April 4, 2017

The Trump administration’s condemnation of the Syrian regime comes after a week of confusion about its position on Assad’s future.

Nikki Haley, the U.S. ambassador to the United Nations, called the Syrian president a “war criminal” who’s done “disgusting things to his own people” at a press conference in New York City on Monday. “We have no love for Assad. We’ve made that very clear,” Haley said, according to Reuters.

But Haley’s statement came just days after she suggested the U.S. was softening its stance on Assad. “Our priority is no longer to sit there and focus on getting Assad out,” she told a group of reporters on Thursday.

This story was updated with Secretary of State Rex Tillerson’s statement Tuesday afternoon as well as Trump’s 2013 comments about intervention in Syria.