Russian Foreign Minister Sergei Lavrov and U.S. Secretary of State Rex Tillerson enter a hall during their meeting in Moscow, Russia, April 12, 2017.

A senior Russian diplomat says Moscow believes that an global probe into last week's chemical attack in Syria should include experts from Brazil, India, Iran and other nations.

Syrian president Bashar al Assad has questioned whether last week's alleged chemical weapons attack actually happened, saying there are "a lot of fake videos now".

Tension between Russian Federation and the USA has heightened following the missile strike launched last Friday by the US against the Shayrat Air Base in central Syria, with Moscow announcing suspending the flight safety agreement with Washington.

As long as Trump remains unwilling to undertake a serious military commitment to overthrowing Assad, I don't see the objective served by the rhetoric of Tillerson and Haley.

The three countries insist that the U.S. and its allies must respect Syria's sovereignty, Lavrov said, stressing that there must be a careful investigation of the chemical weapons incident in Idlib under OPCW auspices.

Syrian Foreign Minister Walid al-Moallem welcomed global inspectors to visit the base Washington said served as a platform for the attack. "Foreign Minister Lavrov and I agreed we would consider further proposals made about the way forward in Syria, including consulting with our allies and coalition members and we will continue discussions about how to find a solution to the Syrian conflict".

The details of the new understandings were not made public, but Syrian foreign ministry officials were invited by Russian Federation and will hold meetings in Moscow on Thursday, following the meeting between the USA official and Putin.

The US has mostly been backing Syrian Democratic Forces (SDF) in the north, who rarely clash with pro-regime forces.

"As for the charges Russian Federation has been concealing the truth Damascus allegedly has chemical weapons..." I wouldn't use the word impossible. The two countries are at odds over multiple issues, including Moscow's continued support for rebels in eastern Ukraine battling against the Kyiv government, and the USA intelligence community's declaration that computer hackers acting on orders from the Kremlin interfered in last year's US presidential election. I think the word impossible is not right.

"Our impression is that the West, mainly the United States, is hand-in-glove with the terrorists". Assad avoided such retaliation only by capitulating to the demand that he destroy his large chemical weapon arsenal.

"Things will work out fine between the United States of America and Russia", Trump said in his tweet. He said the two sides would also discuss disagreements on Syria and how to end the country's six-year civil war.