The decision meets a deadline set by bipartisan members of Congress to figure out the U.S.' role in Yemen's civil war.
Leaders of the three nations met on Friday to discuss the situation in Syria, including a potential military assault on Idlib.
The strikes came just hours after President Donald Trump warned against them.
Fifty-one people died in the attack last month, most of them children.
A U.N. official says 22 children were killed Thursday.
Europe's air traffic control agency said in a statement Wednesday air-to-ground missiles could be launched within the next 72 hours.
The U.S. Ambassador to the United Nations said Monday the U.N. ceasefire in Syria's Eastern Ghouta has failed, but the U.S. has drafted a new one.
Some trapped in the besieged area of Syria's eastern Ghouta region might receive some much-needed aid after months of violence.
A draft cease-fire resolution is being written in the U.N., but there's growing doubt it will get the Security Council's support.
Eastern Ghouta is one of the last rebel-held areas in Syria, and it's been under near-constant bombardment since 2012.
Dozens of people are dead in Syria's Eastern Ghouta after pro-government forces intensified attacks on the area late Sunday.
At least 80 people died in Syria on Tuesday as regime airstrikes increase.