Russian Federation has warned against military action and said it will shoot down rockets fired at its ally.
However, there is some evidence it was sprayed from helicopters, they said.
US Defense Secretary Jim Mattis said the Pentagon is ready to provide options for a Syria strike in response to the suspected chemical attack, but noted the US and its allies are still gathering information.
Syria on Wednesday described US President Donald Trump's threats of missile strikes on the country in response to an alleged chemical attack as a "reckless escalation", state news agency SANA said. In his next tweet the American president stated that American-Russian relations are now the worst in history and also suggested Russia should stop the arms race.
This is in contrast to an incident one year ago in which the US government had video and other evidence of certain aspects of an actual attack by Syrian aircraft, which involved the use of sarin gas.
Russian Foreign Ministry spokeswoman Maria Zakharova hit Trump in a Facebook post: "Smart missiles should fly toward terrorists, not the legal government that has been fighting worldwide terrorism for several years on its territory".
As it looked to head off the threat of Western strikes, Syria said it had invited the Organisation for the Prohibition of Chemical Weapons, which has blamed the regime for previous attacks, to visit the site.
The U.S. did provide Russian Federation with advance warning via military channels shortly prior to the April 2017 missile strike on the Syrian air base believed responsible for a previous chemical weapons attack. "The President has a number of options at his disposal and all of those options remain on the table". "Even if the United States delivers a strike, this won't change the power balance in Syria", the MP said.
On Wednesday, he offered the clearest sign yet of his willingness to attack Syria, declaring that missiles "will be coming" and criticising Moscow for standing by Mr Assad.
In a later tweet, Mr Trump claimed that the "bad blood" with Russian Federation was due to the Special Counsel's Russian Federation investigation into meddling in the 2016 United States election.
Russian Federation has been a dominant theme during Trump's entire presidency, particularly with the appointment of a special counsel to investigate Russia's election interference.
Dez Bryant unexpectedly released from the Dallas Cowboys
Patterson is a return specialist while both Britt and Dorsett likely factor in somewhere on those special units as well . That's a huge wow?? take 2 I'm ranting and going off on the media whenever I'm just being normal Dez in my everyday life.
In the past, Trump has condemned others for forecasting military plans, repeatedly blistering President Barack Obama during the 2016 campaign.
Earlier this week, the Federal Bureau of Investigation raided the offices and hotel room of Trump's personal attorney, Michael D. Cohen, enraging the president, who called it an "attack on our country in a true sense".
As a private citizen in 2013, Trump was stridently opposed to military intervention against the Bashar al-Assad regime, counseling on Twitter that there is "no upside and tremendous downside" to ousting Assad. Trump called the suspected chemical attack a "barbaric act" and suggested Putin bears some responsibility.
The Russian military said later it had observed movements of United States naval forces in the Gulf.
"We should all be outraged at these horrific reports and images from Douma", said Peter Salama, the United Nations agency's chief of emergency response.
Trump spoke with French President Emmanuel Macron and UK Prime Minister Theresa May on Tuesday, whose government officials are also in the midst of extensive consultations with each other about launching a military strike as early as the end of this week.
If any Russians are killed in USA reprisals for Saturday's attack, Moscow could step up harassment of US warplanes and outposts in the region, former officials say.
"I don't want to telegraph what I am doing or what I am thinking", Trump said. Two irreconcilable things have been thrown into the scale: the posture of a strong leader and the danger of an armed conflict between Russian Federation and the US. "We'll see what happens".
The most prudent path is the one already announced by the president: to withdraw USA forces from Syria's civil war and use the United States' unparalleled diplomatic power to pursue a viable detente in Syria.
While Trump's tweet did not disclose the exact date and time of a US missile strike, Assad's allies are lining up to back the Syrian regime.
At the eye of the storm, Assad said any Western action "will contribute nothing but an increase in instability in the region, threatening worldwide peace and security", Syrian state television reported. Israel has not confirmed launching the attack, which reportedly killed 14 people, including seven Iranians.