And now the U.S. and its allies, including the United Kingdom, are considering whether to hit Syria over a suspected poison gas attack that medical relief organisations say killed dozens of people in the rebel-held town of Douma near Damascus on Saturday.
Russia- which backs Syrian President Bashar al Assad-has warned of a response if Western nations strike Syrian government facilities.
In February, Israel suffered the rare embarrassment of losing an F-16 jet during an operation against targets in Syria.
The Eurocontrol airspace organization said that the European Aviation Safety Agency had sent a "Rapid Alert Notification" that flight operators needed to consider the possibility of air or missile strikes on Syria.
The Syrian government and Russian Federation, which backs Assad, have denied a chemical attack took place.
"Israel, Saudi Arabia, and even elements within the U.S. government are likely to try and use this situation to push Trump to assume a more forceful position against Iran on the ground in Syria", Barnes-Dacey added.
The Russian military said the US strike force was due to arrive in the Middle East at the start of May.
The Khan Sheikhun attack prompted Trump to order US missile strikes on the Syrian airfield from which USA officials said the government's planes launched the attack.
"That significantly limits the number of options available to the United States, because the Russians are embedded in many cases with the Syrians". This time, he's under pressure to hit harder and take bigger risks. "Do you do something symbolic and meaningless just to show you did something?" said Philippe Moreau Defarges, an adviser at the French Institute for International Affairs. Trump said in a tweet in which he also claimed success in the fight against the Islamic State in Syria and elsewhere, but said he was not getting enough credit.
Unless someone can inject some coherence into Trump's scattershot approach to Syria, a missile attack could do more harm than good.
Mr Peskov said the Kremlin was closely following Syria-related announcements from Washington and reiterated a Kremlin call for restraint.
Thursday 09:48: Brexit secretary David Davis - who opposed action against Assad when David Cameron was the prime minister, has said that he does not have the same concerns about striking Syria as he did then, Mirror Online reports.
Watch Morning Joe react to the tweet above. Assad has done it several times, though never on such a scale as last week.
A chemical attack is reported to have taken place last Saturday in Douma, where the rebel group Jaish al-Islam controls territory. Nor will they stop Turkey from attacking America's Syrian Kurdish allies - and possibly US troops. On Thursday, May's cabinet agreed on the need to respond.
Trump is scrapping plans to travel this week to a summit in South America due to the situation in Syria, the White House said Tuesday.