"No", Trump said. But, he added, "I see them using gas ... we have to do something".
Tillerson reiterated Washington is "quite confident" that the recent chemical attack was planned and executed by Syrian government forces, which involved chlorine bombs and other chemical weapons on more than 50 occasions.
The two top diplomats had sat down together earlier in the day to work through the fallout of last week's chemical attack in northwestern Syria, which plunged the old Cold War enemies to a new low. "We're going to see how that all works out", Trump said.
The comments are expected to clear the air amid speculations that last week's USA missile attack against a Syrian airfield was the stepping stone for a major invasion. We may be at an all-time low in terms of a relationship with Russian Federation. Trump said the attack was in response for an alleged chemical attack that killed over 80 people in Syria last week.
Russia's Safronkov called the USA strikes on a Syrian air base in retaliation for the Khan Sheikhoun a provocation, but Delattre said they were "a legitimate response to a mass crime which could not go unpunished".
It was the eighth veto by Russian Federation, a close ally of Syrian President Bashar Assad, on a Western-backed Syria resolution and reflected the deep division that has left the U.N.'s most powerful body struggling to tackle the use of banned chemical weapons and to help end the six-year Syrian conflict.
Lavrov gave Tillerson an icy welcome Wednesday, diving straight into Moscow's grievances with Washington in what would usually be warm opening remarks.
According to an official Russian interpreter. Tillerson sidestepped the question, but Lavrov said Russian Federation had seen no proof for the "slanderous" accusation.
Tensions between Moscow and Washington have further aggravated over Syria after the US missile strike on a Syrian military airfield Thursday, which it claims to be in response to the alledged Syrian government's chemical weapons attack last Tuesday in Khan Sheikhoun.
Mr Lavrov called for a United Nations investigation into the attacks in Syria beforehand but no agreement was reached with Washington during the two-hour talks. "I would like to say again that we never saw any facts; anything that would look even remotely like facts [to prove this]".
He said: "So Russia faces a choice: it can continue acting as a lifeline for Assad's murderous regime, or it could live up to its responsibilities as a global power, and use its influence over the regime to bring six long years of failed ceasefires and false dawns to an end". And to further clarify areas of sharp difference, so we can better understand why these differences exist and what the prospects for narrowing those differences may be.
Russian Federation had earlier vetoed a United Nations resolution demanding the Syrian government cooperate with an investigation of the suspected chemical attack, saying that Moscow had consistently expressed its "categorical disagreement" with the draft resolution, which led to further criticism from the West including the US. "Where is the proof that Syrian troops used chemical weapons?"
The US position on Syria is still woefully unclear, as Trump has made no comprehensive statement on Syria since last week's missile attack. As the Federal Bureau of Investigation and multiple congressional committees investigate potential collusion between Russia and Trump's campaign in last year's USA election, Trump can point to his hard-line stance as fresh evidence that he's far from beholden to the Russian leader.
Tillerson said he hoped the Syrian people would choose to oust Assad and reiterated that defeating ISIS was the United States first priority in Syria.
Adding to more confusion, US Defense Secretary James Mattis has said that while defeating ISIS was the first priority, further use of chemical weapons by the Assad regime would not be tolerated and could warrant additional military action.