The Trump administration knew that Syrian dictator Bashar al-Assad was repeatedly attacking his own citizens with toxic chemicals. But the White House tacitly endorsed his continuing rule anyway.

That was the subtext to President Donald Trump’s message Wednesday, when he revealed that the U.S. was aware of a series of chlorine gas attacks leading up to this week’s deadly suspected sarin strike that killed dozens of civilians in an opposition-held town.

And yet, while the toxic bombs were falling, Trump’s administration repeatedly signaled that it would do nothing to remove Assad—a policy shift the Syrian dictator may have taken as a green light that led to Tuesday’s chemical massacre.

“If you look back over the last few weeks, there have been other attacks using gas,” Trump said during a Rose Garden press conference. “You’re now talking about a whole different level,” he said, condemning Tuesday’s attack together with Jordan’s King Abdullah II, but revealing he’d just possibly been willing to let the others slide.

The White House, U.S. intelligence agencies, and the military’s Central Command all declined to elaborate on Trump’s comments, but he seemed to confirm reports from rebel groups and aid organizations of multiple suspected gas attacks in the past two weeks.

“At around 6 pm on 25 March, Latamneh hospital in northern Hama governorate was targeted by a bomb dropped by a helicopter, which hit the entrance of the building. Information collected by the hospital medical staff suggests that chemical weapons were used,” according to a statement from Doctors Without Borders. “Immediately after the impact, patients and staff reported suffering severe respiratory symptoms and burning of mucous membranes—symptoms consistent with an attack using chemicals.”

“No doubt there is chlorine in these gases, there is a strong smell of chlorine on the patients. But we suspect it was mixed with a number of other chemicals as well, because of the fatalities we had. Chlorine itself doesn’t normally cause that much death,” added Dr. Shajul Islam in a video made the following day, one of a number of social media posts about the attacks deemed credible by Western intelligence services.

The strike on Latamneh was one of nine suspected chemical weapons attacks since the beginning of this year reported by the Syrian Network for Human Rights, an independent watchdog group.

On March 26, Latamneh was hit again by a barrel bomb containing chlorine ammunition, according to the Izza Army, a rebel group. Three days later, the opposition reported that 35 people were affected when a Grad missile loaded with chlorine hit the al Qaboun suburb in eastern Damascus. On March 30, rebels said that the regime helicopters bombarded Latamneh again with barrel bombs containing chlorine ammunition and that dozens were affected. Local opposition media reported that the affected suffered vomiting, unclear vision, giddiness (dizziness), and difficulty breathing.

That same day, Secretary of State Rex Tillerson announced that the “longer-term status of President [Bashar] Assad… will be decided by the Syrian people,” a comment seconded by the White House spokesman Sean Spicer and widely understood as U.S. willingness to accept Assad remaining in office. “Well, I think with respect to Assad, there is a political reality that we have to accept,” Spicer said.

It took Tuesday’s reported aerial bombardment of rebel-held Khan Sheikhoun in Idlib province—and the images of dead babies—to reach into the head of the occupant of the Oval Office.

“That attack on children yesterday had a big impact on me—big impact,” Trump said.

The Trump White House’s reluctance to respond shows that its strategy on Syria and ISIS is still in its infancy, leaving Trump now in the position of reacting to Assad’s violence—or relying on Moscow to make Assad obey, even as Russia is refusing to condemn its ally. Moscow is backing Syrian regime claims that an airstrike hit a rebel weapons cache , and that the chemical weapons come from there.

Rather than seeing the earlier gas attacks as Assad possibly testing the Trump administration, Trump blamed the Obama administration for yesterday’s attacks, calling them “a consequence of the past administration’s weakness and irresolution,” in a formal statement condemning the killings.

“I now have responsibility, and I will have that responsibility and carry it very proudly,” Trump said Wednesday, responding to a reporter’s question on how a White House statement this week blamed the Syria attack in part on Obama administration foreign policy. “My attitude towards Syria and Assad has changed very much.”

But Sen. Marco Rubio said that’s dodging responsibility for the messages his White House and secretary of State sent a brutal dictator.

“If you’re Bashar al-Assad, and you read that it’s no longer a priority for the United States to have you removed from power… then that is an incentive to act with impunity,” said the Florida Republican Wednesday.

Tillerson’s reaction to the attack on Tuesday called on Russia and Iran to “exercise their influence over the Syrian regime and to guarantee that this sort of horrific attack never happens again,” yet another signal to Assad that the U.S. would let this go, and a strategy that drew jeers from Democrats on Capitol Hill.

“It was a Russian aircraft piloted by an Assad pilot that dropped a weapon that had the effect that reminds us of sarin,” Sen. Ben Cardin, top Democrat on the Senate Foreign Relations Committee said. “We need action: for me, it starts with a clear U.S. policy that President Assad has… no future as the leader of Syria,” and Russian leader Vladimir Putin held responsible for supporting him. “He needs to be investigated for culpability as a war criminal,” Cardin said.

But some of the Syrian opposition’s American representatives were hesitant to criticize the Trump administration for its about-face. Instead, like Trump, they blamed the previous administration for allowing Assad’s toxic attacks to continue.

“Obama set up this unfortunate precedent where chlorine attacks are basically ignored,” said Kenan Rahmani, with The Syria Campaign, a pro-opposition group. After a horrific sarin gas attack in 2013, Washington struck a deal with Moscow and Damascus to remove the regime’s most dangerous chemical weapons. But chlorine, a household item, has never been banned by international treaty the way sarin or mustard gas has. In the intervening years, there have been dozens and dozens of reported chlorine attacks. “President Trump was right… the Obama administration created a sense of impunity for the Assad regime.”

Former Syrian premier-turned-rebel-negotiator Dr. Riad Hijab, the chief coordinator of the Syrian opposition’s High Negotiations Committee, praised Wednesday’s tough talk after he said Trump officials initially seemed to be giving Assad a pass.

“Trump needs to turn his words into action… What we ask from Mr. Trump is to destroy all the chemical weapons. And the toxic gas. And all the carriers—the missiles, the air planes, and the air bases,” he said in an interview in Washington, D.C., ahead of meetings with Trump officials.

The former Syrian prime minister, who defected in 2012 with the help of the Free Syrian Army, said officers from the Syrian WMD program have told him that the regime did not give up all its stockpiles nor dismantle all its production lines.

“He has the experience, the expertise, and the equipment,” and the will to keep using chemical weapons, Hijab said of Assad.

Hijab dismissed the UN-led Geneva process meant to broker a political solution to the crisis as a way for Russia and Iran to buy more time for the regime to keep killing.

“This is a meaningless discourse,” he said, griping of five useless rounds of talks in 2016. “It will not protect Syrians.”

—with additional reporting by Tim Mak and Asawin Suebsaeng