A political solution to the war in Syria is not possible with President Bashar al-Assad in power, the U.S. ambassador to the United Nations has said in an apparent hardening of the Trump administration's position.
In comments for a Sunday broadcast on CBS television ("Face the Nation"), Tillerson said "the first priority is the defeat of ISIS", and "Once the ISIS threat has been reduced or eliminated, I think we can turn our attention directly to stabilizing the situation in Syria".
Rather, the U.S. Tomahawk missile strike was meant to be "a strong signal" to Syria not to use chemical weapons again.
He challenged Russian Federation publicly in a way Trump appeared scrupulously to avoid and said of Assad early Thursday: "It would seem that there would be no role for him to govern the Syrian people".
"I think the president has authorization to use force", he said.
US -backed rebels groups have long pleaded for more USA intervention and complained that Washington has only fought the Islamic State group.
With no direct threat to US national security and with no congressional authorization, Trump's use of force was illegal.
"There's not any sort of option where a political solution is going to happen with Assad at the head of the regime", Nikki Haley told "State of the Union" program. "The consequences of this for regional and global stability could be extremely serious", Russia's deputy UN envoy, Vladimir Safronkov, told a meeting of the UN Security Council on Friday.
Dozens of representatives of the media, local authorities, and emergency services have visited the airfield since the attack, with no alleged "storage units" or chemical weapon shells being found, the ministry said in a statement, calling on a mission of professional experts to be sent to the air base. Almost 80 people died in Khan Sheikhoun town in the rebel-held northern province of Idlib on 4 April after Syrian planes allegedly carried out gas attacks, which the USA said was the banned nerve agent sarin.
Nikki Haley, the US ambassador to the United Nations, said "getting Assad out is not the only priority" and that countering Iran's influence in Syria was another.
Rouhani said "neutral countries should come and assess to make it clear where the chemical weapons came from".
Donald Trump's bombing of a Syrian airfield last week has triggered a global power play involving North Korea's nuclear program, Russia's strident support of Bashar al-Assad and the movement of USA warships to global hotspots.
Elsewhere in the region, a leading Iraqi Shiite cleric and militia leader, Moqtada al-Sadr, called on Assad to step down and "save Syria before it's too late".
"The failure related to the recent strike and the recent awful chemical weapons attack in large measure is a failure on Russia's part to achieve its commitment to the worldwide community", Tillerson said in an interview aired on ABC on Sunday.
The decision by Johnson to cancel a visit to Moscow later this month shows a lack of understanding of events in Syria, Russia's Foreign Ministry said on Sunday.
That doesn't mean Russian Federation is without fault, Tillerson said.