2. The protests came amid the wider Arab Spring, which felled leaders from Tunisia to Egypt to Libya.
3. In Syria, protesters called for political reforms. Assad’s family has ruled the country since 1971; his Baath party has ruled since 1963.
4. Assad responded brutally, unleashing a campaign of kidnapping and torture. In April 2011, he deployed the army to put down protests. Many were killed.
5. According to the Syria Observatory for Human Rights, 110,000 people have been killed in the conflict over the past two and a half years.
6. Assad’s critics, such as satirical cartoonist Ali Ferzat, have been met with violence. Ferzat was kidnapped and beaten by security forces in August 2011.
7. Both of his hands — used for drawing — were shattered. He went into exile.
8. Ibrahim Qashoush, a popular protest singer, was found dead, his throat carved out of his corpse.
Protesters sing one of Qashoush’s most well-known songs.
10. As the crackdown continued, the U.S. slapped sanctions on Assad and six of his advisors. In August, Obama made his first call for Assad to step down, saying: “For the sake of the Syrian people, the time has come for President Assad to step aside.”
11. Two months later, the United Nations Security Council voted on a resolution to bring new sanctions against Assad unless he halted his crackdown. Russia and China vetoed the resolution, something they would do several times over.
12. The army continued to lay siege to Homs until it was reduced to rubble.
13. Marie Colvin, a legendary war correspondent for The Sunday Times (U.K.), was one of the only journalists in Homs. She was killed when the safe house she was staying in was shelled in February 2012. Here’s her last report.
Turkish journalists holding photographs of their colleagues who died in Syria recently. From left: Anthony Shadid, Remi Ochlik, and Marie Colvin stage a protest outside the Syrian embassy in Ankara, Turkey, Friday, Feb. 24, 2012. They protested against the Syrian regime and called on the U.N. and democratic countries to protect journalists working in Syria.
14. The rebels loosely organized into the Free Syrian Army (FSA).
15. In May 2012, the regime unleashed a massacre at Houla, killing more than 100 people, many of them women and children.
16. They also targeted Aleppo, once a beautiful ancient city and Syria’s largest.
17. The regime launched repeated air strikes on Aleppo and around the country.
18. This is what the aftermath of an air strike looks like (Warning: graphic images):
19. The U.S. funneled humanitarian and non-lethal aid to the FSA, while Qatar and Saudi Arabia provided a steady flow of arms, often via Turkey.
20. Syria, meanwhile, was backed by Iran. Hezbollah, an Iran-backed militant group based in neighboring Lebanon, sent militants to Syria to fight for Assad.
Assad with Hassan Nasrallah, the leader of Hezbollah.
21. Vladimir Putin has supplied Assad, Russia’s last major ally in the Middle East, with a steady flow of weapons and other support.
23. That meant Syria wasn’t just facing a civil war internally, but also a proxy war more broadly, pitting Gulf states like Saudi Arabia against Iran, with both sides fighting for supremacy in the region.
24. To make things more complicated, foreign Sunni extremists linked to al-Qaeda flooded into Syria to join the fight against Assad.
25. Rebels also committed horrific atrocities. Video emerged showing a rebel eating the heart of a regime soldier.
26. Information was hard to come by, with journalists facing kidnapping and violence from the regime and rebels alike. American freelance journalist James Foley has been missing for nearly a year.
27. In response to a question on Aug. 20, 2012, Obama said that he would consider the use of chemical weapons in the Syrian conflict, a “red line” that “would change my calculus.”
31. On one day last month, around 10,000 refugees walked from Syria into Iraqi Kurdistan.
32. Obama’s “red line” appeared to have been crossed on Aug. 21, 2013 when images of a chemical attack that the U.S. says killed more than 1,400 people in a Damascus suburb flooded social media.
This heartbreaking video claims to show a child suffering from the effects of a chemical weapon. (Warning: Extremely graphic)
34. Assad has denied responsibility for the attack.
35. On Aug. 26, Kerry said use of chemical weapons was a “moral obscenity.” He began making the case for limited military strikes against Assad.
36. Amid the march to war, Obama shocked everyone by saying he would take his Syria plans to Congress for a vote.
39. Others said the delay was a sign of weakness and has given Assad time to move key weapons and supplies.
41. And some have asked, why Syria? People are dying all over the world. Should the U.S. really act as the world’s policeman?
42. Chemical weapons are seen as beyond the pale.
The international community began addressing the horror of chemical weapons in the wake of World War I, when they were first deployed on a mass scale. They were banned by the 1925 Geneva Protocol, to which Syria is a signatory, and by the 1992 Chemical Weapons Convention, to which it is not.
43. But it’s not just about chemical weapons. The administration also says they need to enforce U.S. credibility, and also send a message to countries like Iran that weapon of mass destruction are inadmissible.
In the midst of the Syria crisis, Mahmoud Ahmadinejad (above) left office and was replaced as Iranian president by Hassan Rouhani. Rouhani, elected in June 2013, once led Iran’s nuclear negotiating team and has advocated better relations with the West.