BEIRUT — The international chemical weapons watchdog said Tuesday it was sending a fact-finding mission to the Syrian town where a suspected chemical gas attack took place over the weekend, following a request from the Syrian government and its Russian backers that appeared to be aimed at averting punitive Western military action.

It was not immediately clear whether the announcement would delay or prevent a U.S. strike in Syria. President Donald Trump has vowed to respond “forcefully” to Saturday’s attack on civilians in the town of Douma, hours before rebels agreed to surrender it, and warned that Russia — or any other nation found to share responsibility — will “pay a price.”

In a statement, the Organization for the Prohibition of Chemical Weapons said a fact-finding mission was “preparing to deploy to Syria shortly,” though it did not give a more precise timetable on when the inspectors would arrive.

Trump on Tuesday cancelled plans to travel to South America later this week, choosing to stay in the United States to manage the response to the events in Syria. The White House said he later spoke with British Prime Minister Theresa May and the two “agreed not to allow the use of chemical weapons to continue.”

Trump also discussed Syria with French President Emanuel Macron, who said Tuesday that France would decide in the coming days on “a strong and joint response” with the U.S. and Britain to the suspected attack.

The incident has sparked international outrage and ratcheted up tensions in the already volatile Mideast, raising the specter of possible imminent American retaliation amid Russia’s warnings against any such action, and denials that any chemical weapons attack took place.

Adding to the tensions, Iran, a strong ally of Syrian President Bashar Assad, threatened to respond to an airstrike on a Syrian military base on Monday that the Syrian government, Russia and Iran have blamed on Israel.

Seven Iranians were among the estimated 14 people killed in the missile strike, and a senior Iranian official visiting Damascus said the attack “will not remain unanswered.” Ali Akbar Velayati, an aide to Iran’s supreme leader, spoke upon arrival in the Syrian capital on Tuesday.

The Syrian air base was struck by missiles a little more than 24 hours after the alleged chemical attack. Israel does not typically comment on its operations in Syria, and it is unclear whether the missile attack was linked to the alleged use of chemical weapons.