President Donald Trump said Friday that he ordered U.S. forces to begin bombing specific sites in Syria with allies to retaliate for an "evil and despicable" chemical weapons attack by President Bashar al-Assad’s regime — saying that "we are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents."

"A short time ago, I ordered the United States Armed Forces to launch strikes on targets associated with the chemical weapons capabilities of Syrian dictator Bashar al-Assad," Trump told the nation in a speech from the Oval Office.

"A combined operation with the armed force of France and the United Kingdom is now underway," Trump said. "We thank them both."

The Associated Press reported that loud explosions were lighting up the skies over Damascus as Trump announced the offensive.

Explosions could be heard immediately after the president spoke, Reuters reported.

A U.S. official told Reuters the strikes were aimed at multiple targets and involved Tomahawk cruise missiles.

Criticizing Russia

The U.S. earlier Friday slammed Russian President Vladimir Putin for failing to stop Assad in the April 7 chlorine gas attack, which killed at least 60 people and injured 1,000 others in the town of Douma, near Damascus.

"The purpose of our actions tonight is to establish a strong deterrent against the production, spread and use of chemical weapons," Trump said. "Establishing this deterrent is a vital interest of the United States.

"The combined response to these atrocities will integrate all instruments of our power: economic and diplomatic.

"We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents," Trump said.

Trump's speech reflected a tougher stance toward Iran and particularly Russia, calling them "two governments most responsible for supporting, equipping and financing the criminal Assad regime.

"To Iran and to Russia, I ask what kind of a nation wants to be association with the mass murder of innocent men, women and children?" Trump posed.

"The nations of the world can be judged by the friends they keep.

"No nation can succeed in the long run by promoting brutal tyrants and murderous dictators," he said.

President Trump noted that Putin promised to guarantee the elimination of chemical weapons in Syria in 2013.

"Assad's chemical attack and today's response are the direct result of Russia failing to keep that promise," Trump said. "Russia must decide if it will continue down this dark path or if it will join with civilized nations as a force for stability and peace. Hopefully, someday we'll get along with Russia and maybe even Iran, but maybe not."

The bombing followed Trump's Twitter warning to Moscow on Wednesday to "get ready" because missiles would be "coming, nice and new and 'smart.'"

He then tweeted Thursday that a possible strike "could be very soon or not so soon at all."

Taking Aim at Assad

President Trump's posts came after French President Emmanuel Macron said Tuesday that believed Syria used the weapons in violation of United Nations resolutions and that a decision on how to respond would come from France, the U.S. and the U.K, "in the coming days."

Macron said any attack would be aimed at the Assad regime's chemical "capabilities" and not at its Iranian and Russian allies.

Russian Foreign Minister Sergei Lavrov said Friday that the Kremlin had "irrefutable evidence" that the chemical attack was staged by Britain.

In announcing the action, Trump explained that the U.S. responded with 58 missile strikes last year after Assad launched "a savage chemical weapons attack against his own innocent people." Those strikes destroyed 20 percent of Syrian's air forces, he said.

"Last Saturday, the Assad regime again deployed chemical weapons to slaughter innocent civilians near the Syrian capital of Damascus," Trump said. "It was a pattern of chemical-weapons use by the very terrible regime."

"The evil and despicable attack left mothers and fathers, infants and children thrashing in pain and gasping for air," Trump said. "These are not the actions of a man. They are crimes of a monster instead."

The president said "following the horrors of World War I a century ago, civilized nations joined together to ban chemical warfare. Chemical weapons are uniquely dangerous, not only because they inflict suffering but because even small amounts will unleash widespread devastation."

British Prime Minister Theresa May said she had authorized British armed forces “to conduct coordinated and targeted strikes to degrade the Syrian regime’s chemical weapons capability.”

The military action is not about intervening in Syria’s civil war or changing its government, she said.

Newsmax wires contributed to this report.