As for Washington's claims about the Syrian military's "preparations for another chemical weapons attack" in general, Pushkov suggested that these kinds of accusations were on par with the "fake news bullsh*t" put out by mainstream media networks like CNN.
"It appears that they took the warning seriously", Mattis told reporters flying with him to Brussels for a meeting of North Atlantic Treaty Organisation defence ministers.
A non-governmental source with close ties to the White House said the administration had received intelligence the Syrians were mixing precursor chemicals for a possible sarin gas attack in either the east or south of the country, where government troops and allied forces have faced recent setbacks.
In an ominous statement issued with no supporting evidence or further explanation, Press Secretary Sean Spicer on Monday night said the U.S. had "identified potential preparations for another chemical weapons attack by the Assad regime that would likely result in the mass murder of civilians, including innocent children".More news: Premier League Fixtures 2017/18 - when are the biggest games?
Syria and its allies, Russian Federation and Iran, have rejected the USA allegation and say Assad's forces never previously used chemical weapons.
In reaction to what the USA said was a gas poison attack by the Assad regime back in April, President Trump ordered a strike on a Syrian Shayrat airfield base.
Mr. Mattis said: "You better ask Assad about that".
Washington launched a retaliatory cruise missile strike days later against the Shayrat airbase - the first direct United States action against the regime, which denies any use of chemical weapons.
The latest chemical attack in Syria occurred in April, which killed more than 80 civilians and wounded hundreds.More news: NATO chief: US allies to spend $12 billion more this year
According to a US intelligence official who preferred to be anonymous, the warning was issued amid new reports that there was abnormal activity that might be connected with preparations for a chemical launch.
The Syrian military and foreign ministry did not comment on the White House warning, although state-run al-Ikhbariya television station said the allegations were fabricated.
Russian Federation dismissed the White House assertions that a strike was being prepared as "unacceptable".
Russian Federation has supported the Syrian regime since 2015 with air strikes against what it says are Islamist extremists. "I would like to think that the president saved many innocent men, women and children".
"As we have previously stated, the United States is in Syria to eliminate the Islamic State of Iraq and Syria". The fact is we are in Syria to destroy ISIS. A Pentagon spokesperson said the activity was from "the past day or two". Artillery struck back in retaliation, a Turkish military statement said. President Tayyip Erdogan has said Turkey would not flinch from taking tougher action against the YPG in Syria if Turkey believed it needed to.More news: Trump accepts Macron invite to attend Bastille Day parade
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