Nikki Haley, the USA ambassador to the United Nations, described regime change in Syria as a U.S. priority and inevitable, while Mr Tillerson suggested that last week's American air strikes in retaliation for the chemical attack had not really changed USA priorities toward ousting the Syrian leader.
Trump blamed Syrian President Bashar Assad for the attack and called on the global community to join him in trying to end the bloodshed.
February 28, 2017: Russian Federation, a stalwart ally of the Syrian government, and China veto a U.N. Security Council resolution authorizing sanctions against the Syrian government for chemical weapons use.
No 10 reiterated the Government's backing for the USA action ordered by President Donald Trump in response to the regime's latest use of chemical weapons against its own people.
"Now, the administration has leverage it should test with the Assad regime and Russian Federation to restrain Syria's air force, stop any use of chemical or biological weapons, implement an effective cease-fire in Syria's civil war and even move toward a negotiated transition of power - goals that eluded the Obama administration".
Eighty-nine people, including 33 children and 18 women, died in the suspected nerve agent attack in the rebel-held town of Khan Sheikhoun on Tuesday.
In a speech on Sunday, Rouhani also criticised USA -allied Gulf Arab states for endorsing the US missile strike. But the Obama plan was created to be substantial enough to have an impact on Assad's calculus.
"What we are focused on is building worldwide support for a political solution to end the conflict and bring lasting peace and stability to Syria", Mrs May's spokesman said.
SpaceX's historic re-launch of orbit-class booster
The company has now shown that the rockets can be re-used, which will lower the cost of space missions and space flights . Elon said the feat means it can fly and refly an orbital class booster, which is the most expensive part of the rocket.
"What we had in mind in 2013 had many more targets and was much more expansive", a senior Obama administration official involved in those discussions told me.
October 14, 2013: Syria becomes a signatory to the Chemical Weapons Convention, prohibiting it from producing, stockpiling or using chemical weapons.
US goals in the region, McMaster said, are "the defeat of ISIS" and "a significant change in the nature of the Assad regime and its behavior in particular". The Security Council threatens to authorize the use of force in the event of non-compliance.
Once the threat from Islamic State has been reduced or eliminated, "I think we can turn our attention directly to stabilizing the situation in Syria", Tillerson said in excerpts from an interview on CBS's "Face the Nation", that will air in full on Sunday.
"The Syrian people and army are determined to crush terrorism in every part of Syrian territory".
"There's no doubt the USA action is a game-changer in Syria".
The cancellation "once again confirms doubts about the added value of dialogue with the British, who don't have their own position on the majority of current issues", the foreign ministry said in a statement.
Sen. Lindsey Graham (R-SC) did not mince words - or letters - when he remarked on Bashar al-Assad's flippant attitude toward President Trump on Sunday's "Meet the Press".