The U.S. attack on a Syrian air base Friday morning came after years of heated debate and deliberation in Washington over intervention in the bloody civil war.
Chemical weapons have killed hundreds of people since the start of the conflict, with the U.N. blaming three attacks on the Syrian government and a fourth on the Islamic State group.
Here's a timeline of this week's events:
April 4, 2017
One of the worst chemical attacks came Tuesday in rebel-held northern Idlib where dozens were killed in the town of Khan Sheikhoun. Witnesses said the attack was carried out by either Russian or Syrian Sukhoi jets. Moscow and Damascus denied responsibility.
That attack prompted President Donald Trump, on day 77 of his presidency, to dramatically shift U.S. policy on Syria. Trump issued a statement saying that the heinous actions of Syrian President Bashar Assad's government are the direct result of Obama administration's weakness and irresolution.
After the attack, hospitals around Khan Sheikhoun were overwhelmed, and paramedics sent victims to medical facilities across rebel-held areas in northern Syria, as well as to Turkey.
April 5, 2017
Trump says Assad's government had crossed a lot of lines with the chemical attack in Syria. At a joint Rose Garden news conference alongside Jordanian King Abdullah II, Trump said the attack "cannot be tolerated.
April 6, 2017
The U.S. fired a barrage of cruise missiles into Syria Friday morning in retaliation for the chemical weapons attack against civilians. Trump said strike on Syria in the vital national security interest of the United States.
April 7, 2017
Syria decried a U.S. missile attack on a government-controlled air base where U.S. officials say the Syrian military launched a deadly chemical attack earlier this week, calling it an aggression that led to losses.
A Syrian opposition group, the Syrian Coalition, welcomed the U.S. attack, saying it puts an end to an age of impunity and should be just the beginning.
Major Jamil al-Saleh, a U.S-backed rebel commander whose Hama district in the country's center was struck by a suspected chemical weapons attack, said he hoped the U.S. attack on a government air base would be a turning point in the six-year war.
Source: Voice of America