McCain - who vocally supported the US military response to the attack - added that the White House must put forward a detailed Syria strategy.
But President Vladimir Putin has not himself the US airstrike, and some reports suggest he is unhappy that Assad has boxed him into defending what many consider a war crime.
"So you know, of course, it's to defeat ISIS". I think we ought to ask them a question.
Haley told CNN in an interview that Trump and his administration were shown classified information proving that Syrian President Bashar Assad had been involved in the alleged chemical attack against civilians in Syria's Idlib.
And if we would want to appeal rationally to Russia, this is a great opportunity for the Russian leadership to reevaluate what they're doing.
The Trump administration had seemed ambivalent over whether it would push for regime change in Syria.
Meanwhile, Russia and Iran, President Assad's key military backers, are threatening retaliation if there are any further American air strikes and the task of breaking the present deadlocks over Syria remains enormous.
Speaking on CBS's Face The Nation, Mr Tillerson said there was no evidence to suggest Russian Federation was part of the alleged chemical attack.
Several lawmakers said Sunday that decision shouldn't entirely be up to Trump.
Jennifer Garner and Ben Affleck Attend Church Easter Sunday
Ben bravely opened up about his alcohol addiction back in March earlier this year, having spent some time away in rehab. That's bad news for the Batman actor, as he made a lot more dough than his wife during their almost 10 year marriage.
The White House says the call took place on Saturday.
McMaster continued, insinuating that he believed Russian Federation had to be knowledgeable of Syria's plan to launch a chemical attack.
Johnson earlier said that instead of traveling to Moscow, he would now be going to Italy for a Group of Seven (G7) meeting on April 10-11 to build coordinated worldwide support for a cease-fire in Syria.
The Iranian president dismissed reports that Assad's forces were behind a chemical attack as "baseless", according to a statement on the presidency website. "What we saw was a reaction to the use of chemical weapons, something I think many of us supported", he said.
He will continue from there to Moscow for meetings with his Russian counterpart Sergei Lavrov and other officials.
"We deplore Russia's continued defense of the Asad regime even after the chemical weapons attack on innocent civilians".
But he said the United States expected Russian Federation to take a tougher stance by rethinking its alliance with Assad because "every time one of these horrific attacks occurs, it draws Russian Federation closer into some level of responsibility".
The South Carolina Republican and military hawk is calling for as many as 6,000 more USA troops to help defeat the Islamic State terror group in the Middle East.
But speaking on ABC News's "This Week, " Tillerson emphasized that the Syrian people would eventually decide Assad's fate.