The US President tweeted that the air strikes would be coming "nice and new and smart".
Moscow and London are already involved in an intense diplomatic row after the UK accused Russia of using a nerve agent to poison a former Russian spy, Sergei Skripal, in the UK town of Salisbury last month.
"France will not allow any escalation that could harm the stability of the region as a whole but we can't let regimes that think they can do everything they want, including the worst things that violate international law, to act", Macron said.
Some lawmakers criticized Trump's apparent telegraphing by tweet of a missile strike in Syria.
Pressure has been growing on Bashar Al-Assad's regime and its Russian backers since an alleged chemical attack on Saturday against the rebel-held town of Douma. British officials said up to 75 people were killed. Trump said, referring to Moscow's alliance with Assad. A WHO spokesman said, however, the agency cannot say the deadly incident was a chemical attack because it cannot get into the area.
Kupchan said the Kremlin may once have held influence over Assad, when there was a chance he could lose the ongoing civil war.
"You shouldn't be partners with a Gas Killing Animal who kills his people and enjoys it!"
"They (the three leaders) agreed that the international community needed to respond to uphold the worldwide prohibition on the use of chemical weapons, " the statement continued.
Sanders said Trump would speak later with French President Emmanuel Macron and British Prime Minister Theresa May.
"We are still assessing the intelligence - ourselves and our allies", he told reporters alongside his Dutch counterpart Wednesday.
FILE - A child is treated in a hospital in Douma, eastern Ghouta in Syria, after what a Syria medical relief group claims was a suspected chemical attack April 7, 2018.
"Final decisions haven't been made", White House Press Secretary Sarah Sanders said.
The United Nations Security Council met on Tuesday for an urgent discussion on Syria.
Defense Secretary Jim Mattis, who also canceled plans to travel to California in the coming days, sounded a more cautious note.
The AP says the Syrian government and Russian supporters requested the mission. A U.S. Navy guided-missile destroyer, the USS Donald Cook, is in the Mediterranean.
The U.S. has more than 2,000 troops in Syria, and the U.S. -led coalition has launched thousands of airstrikes against the country.
President Trump has cancelled a planned trip to Latin America, which was to begin Friday.
Zasypkin also said that any hostilities with Washington should be avoided, and Moscow was ready for negotiations.
Mario Ritter adapted this story from VOA News for VOA Learning English. Yes, the US has analyzed.