WASHINGTON -- With a decisive airstrike in Syria, President Donald Trump changed his approach to Bashar al-Assad's regime.
At Trump's orders, US warships launched 59 Tomahawk cruise missiles at a Syrian airfield around 3:40 a.m. Friday local time (8:40 p.m. Thursday ET), marking the first US military action against government forces during Syria's six-year civil war.
Before the airstrike, Trump was against military action aimed at Assad's forces. What led to the US President's change of heart? Here are some key details to get you up to speed:
Trump's reversal on military action in Syria can be traced to Tuesday's chemical weapons attack that killed 80 people, including children. US missiles struck the Shayrat air base that housed Syrian warplanes blamed for the attack.
Images of lifeless children killed by sarin became yet another symbol of the international community's failure to help end the bloody civil war.
In one particular photo, a sobbing father clung to bodies of his 9-month-old twins. Others showed children gasping for breath, along with shell-shocked relatives also affected by the gas.
The airstrike hit the rebel-held town of Khan Sheikhoun in northwestern Syria's Idlib province.
As these photos circulated on social media, so did the outrage. Trump was not immune to the horror either and admitted the images changed his thinking on Syria.
"When you kill innocent children -- innocent babies -- babies -- little babies with a chemical gas that is so lethal, people were shocked to hear what gas it was, that crosses many, many lines," the US leader said.
Until the airstrike, Trump gave no indication of what he was planning to do. Then everything changed early Friday in Syria (Thursday night in the United States).
Quoting citizen Donald Trump in 2013: "The President must get Congressional approval before attacking Syria--big mistake if he does not."
— Tim Kaine (@timkaine) April 7, 2017
"Tonight, I ordered a targeted military strike on the air base in Syria from where the chemical attack was launched," he said from his Mar-a-Lago estate in Florida. "It is in this vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons."
He accused Syria of using banned chemical weapons and said such attacks are unacceptable.
The United States started launching airstrikes in Syria in September 2014 under President Barack Obama, but it had targeted only the ISIS terrorist group and not government forces.
Syria described the airstrike as an "erroneous American strategy." Its armed forces said the strike killed six people and wounded several others.
"It makes the United States of America a partner of ISIS, Nusra Front and other terrorist organizations who .... have been attacking Syrian army positions and Syrian military bases," an armed forces' statement said.
The strike occurred during minimal activity at the base and targeted various items, including petroleum and logistical storage, ammunition supply bunkers and air defense systems, the Pentagon said.
To justify the attack, the US military shared an image of a radar track of a Syrian airplane from the airfield flying to the chemical strike area Tuesday. It also showed a second image of bomb damage craters at the air base.
The United States has a "very high level of confidence" that the Syrian regime carried out at least three recent attacks using sarin and nerve gas, US Secretary of State Rex Tillerson said.
Syria has continuously blamed such attacks on terrorists.
Syria's powerful backer, Russia, did not mince words.
The Kremlin said Russian President Vladimir Putin regards the US airstrike as "an aggression against a sovereign state in violation of the norms of international law."
"Vladimir Putin believes that complete disregard for factual information about the use by terrorists of chemical weapons drastically aggravates the situation," its statement said.
It said the airstrikes "dealt a serious blow to Russian-US relations, which are already in a poor state."
Before the airstrike, Russian officials warned the United States against making any "snap judgments" on the chemical weapons attack.
Syria's neighbor, Turkey, had a different reaction.
"Turkey will fully support the steps that will be taken to ensure accountability and to prevent impunity in case of such crimes," it said.
"As a country hosting 3 million Syrians, Turkey will continue its cooperation with the international community to prevent the regime's continued practices of terror and mass punishment."