"Military means will lead us nowhere".
Sanders pushed back against that assertion during a press briefing on Monday. The officials spoke on condition of anonymity to discuss internal discussions.
Defense Secretary Jim Mattis, in separate remarks at the Pentagon, also suggested Moscow bore some blame.
Israel has previously accused Damascus of allowing Iran to set up a complex at the base to supply arms to its ally, Lebanon's Shi'ite Hezbollah.
The stakes are higher for any new U.S. military action, with Trump explicitly mentioning Iran and Russian Federation in connection to the weekend attack.
Trump's tweets were more belligerent - he told Russia "You shouldn't be partners with a Gas Killing Animal who kills his people and enjoys it!" - and declared that USA relations with Russia have plunged to a historic low.
Trump and other Western leaders have vowed a quick and forceful response to Saturday's alleged gas attack, which rescue workers say killed more than 40 people.
"Russia has trashed the credibility of the council", she said. During one speech, he said, "We must as a nation be more unpredictable".
"The only thing I worry about is that it's not going to happen", Corker said on Capitol Hill.
Trump said, however, that Washington was "getting more clarity" on who was responsible for the attack. The Defense Ministry said Syrian defense units destroyed five of the incoming missiles.
U.S. government sources said Washington's assessment of the Saturday attack was that chemical weapons were used. "We're still working on this".
"We are using the veto in order to protect worldwide rule of law, peace and security, to make sure that you do not drag the Security Council into your adventures", Nebenzia said to Washington.More news: Warmer Temperatures Arrive Wednesday and Thursday!
A team from the Organisation for the Prohibition of Chemical Weapons (OPCW) is due to deploy to Syria "shortly" to determine whether banned weapons were used in Douma. The European Union also said evidence pointed to the use of chemical weapons by Assad's forces.
"We are studying the situation extremely closely, we are meeting with our military and everybody else and we'll be making some major decisions over the next 24 to 48 hours".
Russia's United Nations ambassador, Vassily Nebenzia, urged inspectors from the watchdog agency to fly to Syria's capital today and visit the site in a nearby rebel-held town. "We have a lot of options militarily", he told reporters.
The US State Department said on Monday that the Douma victims' symptoms were consistent with those caused by a nerve agent but they could not confirm what had been used.
Russian Foreign Ministry spokeswoman Maria Zakharova ridiculed Trump, saying on Facebook, "Smart missiles should fly toward terrorists".
Syrian state TV SANA reported that there had been casualties at the base, but Russia said no Russian military advisers were hurt in the attack.
Having worldwide inspectors on the ground in Syria could complicate any forthcoming plans by the Trump administration to bomb or otherwise retaliate against the government of President Bashar Assad.
Those efforts, he wrote, have been hindered by the special counsel's investigation into Russian election meddling. According to Slutsky, "the West's goals are obviously far removed from fighting worldwide terrorism, and its main goal is to oust Bashar al-Assad's regime at all costs, at the cost of lies, provocations and complete fakes". It remains the last stronghold of the anti-regime forces in Syria. AP is the largest and most trusted source of independent news and information.
The incident comes just a week after Trump raised the idea of ending American involvement in Syria.
Such a strike would call on the US's most high-end platforms and present one of the most hard military challenges on Earth.
The FBI seized a number of materials from Trump's longtime lawyer Michael Cohen on Monday, after prosecutors in NY received a referral from special counsel Robert Mueller's team, Cohen's attorney said.
Which brings us to the Question of the Week: What should Trump do about Syria?
Syrian activists on Saturday reported that helicopters had dropped barrel bombs carrying deadly gas onto the rebel-held Damascus suburb of Douma.
It's the second time in recent weeks that Trump has appeared to signal his intentions in Syria ahead of time. It blamed Islamic State militants for mustard gas use.