France and US have said a chemical attack won't be tolerated while Damascus denies it has such weapons. Western countries immediately blamed Damascus for the attack.
But Lavrov on Wednesday called on the West not to stand in the way of what he described as an "anti-terror operation" in Idlib, which borders Turkey.
Foreign Minister Mevlut Cavusoglu has warned Russian Federation that seeking a military solution in Idlib would cause "catastrophe" and trigger an new influx of refugees across its borders.
During their trip, the USA diplomats will reassure Israel of America's support and "underscore that the United States will respond to any chemical weapons attack perpetrated by the Syrian regime".
"We would probably dissolve Tahrir al-Sham because it faces the pressure of Russian Federation and even Turkey".
The American warning follows 10 days of toughly worded exchanges between Western powers on the one side, and Syria and its Russian ally on the other, just as Assad - bolstered by crucial Russian air support since 2015 - sets his sites on Idlib.
"The U.S sees this as an escalation of an already unsafe conflict", Pompeo said on Twitter in a post that also lambasted Russian Foreign Minister Sergei Lavrov for defending Syria's assault plans.
The UN has also requested global parties involved in the Syrian civil war to do everything to prevent open warfare in Idlib, which is home to around three million people.
Pakistan's elite to elect new president as Imran Khan takes the reins
Imran Khan said if members of the government were suspected of any indiscretion, they should also be held accountable. During the marathon session, the prime minister turned down French President Emmanuel Macron's call twice.
Turkey has 12 military observation posts inside Idlib aimed at monitoring a de-escalation zone and media reports have said it has sent concrete blocks over the border to reinforce them in case of an assault. In addition, Russian experts are among the Syrians.
The government has been accused of attacking civilians with chemicals in previous operations, including in Douma near Damascus and in Khan Sheikhun, in Idlib. It comes with an appendix noting that the group's former name was the Nusra Front. "This would not be meant to substantially alter the Idlib battle, but rather to uphold the global convention against the use of chemical arms".
Though the group claims to have no direct ties to al-Qaida, it's considered a terrorist group by the United States and the United Nations.
Russian President Vladimir Putin will attend a three-way summit in Tehran on September, 7, with the leaders of Turkey and Iran, his spokesman said on Friday.
The rights group said a total of 6,036 civilians had been killed in war-torn Syria since January, going on to call on the worldwide community to provide protection to civilians in war-torn Syria and bring the parties responsible for civilian deaths to justice.
She said violence could force as many as 800,000 people to flee in one of the Syrian war's largest displacements yet.
They are to be deployed along with Russian police forces once the government begins occupying Idlib, he said.
After years of war and constant shelling from pro-government forces, the emergency services in Idlib have been reduced to rubble and supplies of critical aid are low, according to medical workers.