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President Donald Trump placed the blame squarely on Assad for Tuesday's sarin attack, which killed at least 86 civilians, saying Thursday evening, "using a deadly nerve agent, Assad choked out the lives of helpless men women and children."
"Years of previous attempts at changing Assad's behavior have all failed and failed very dramatically," said Trump.
Assad, 51, has been in power in Syria for nearly two decades and has been labeled by many a brutal dictator who attempts to crush any rebellion against his authority.
He was born September 11, 1965 to Anisa Makhlouf and Hafez al-Assad, a Syrian politician who rose to the presidency in 1971 and served for nearly 30 years. Before he succeeded his father as president, Assad had been an ophthalmologist.
Assad graduated from the Damascus University in 1988 with a degree in ophthalmology and worked in a military hospital in Damascus, before going to London to continue his medical training, according to the BBC.
In 1994, Assad received news that his older brother Bassel al-Assad, who was a potential successor to his father, was killed in an automobile accident and he returned home to Syria.
Following his brother's death, Assad was groomed to succeed his father, receiving military training in the mid-1990s and taking on roles in the government. In the late 1990s, Assad was charged with leading Syria's relationship with neighbor Lebanon
Upon his father's death in 2000, Assad -- who had risen to the rank of colonel in the Syrian army -- had already consolidated support in the military and the Baath political party, according to a 2015 BBC report, becoming the commander and secretary general of the two, respectively.
The Syrian Constitution was then amended to lower the minimum age to assume the presidency to 34, Assad’s age at the time.
In July 2000, Assad was voted to a seven-year term as president winning 97 percent support in an election in which he was the only candidate. Assad was elected to a second term in 2007 and a third term in 2014.
When he took office in 2000, he promised to be a reformer. But he soon began to crack down on those presenting opposition to his rule, including political opposition, journalists and human rights activists, according to Human Rights Watch.
The Syrian civil war, which is still ongoing, began with protests in March 2011 over the detainment of young boys who had painted anti-Assad and anti-government graffiti on their school walls, according to the Associated Press.
The protests in the months that followed, which called for greater reforms and President Assad to step down from power, became increasingly violent as there were reports of security forces opening fire. In December 2011, the U.N. had estimated that since March more than 4,000 people, including children, had been killed as a result of the military crackdown on protests.
Sitting down for a 2011 interview with ABC News, Assad denied he ordered the crackdown.
He responded to the label he was increasingly receiving from the world outside Syria.
"What's important [is] how the Syrian people look at you, not how you look at yourself," Assad said, adding that public opinion of him outside Syria doesn’t matter.
A suburb of Syria's capital Damascus was attacked on August 21, 2013 using the nerve gas sarin, the same chemical agent used in the attack on Tuesday. U.S. intelligence placed the death toll of that attack at over 1,400 Syrian civilians, including hundreds of children. Assad has denied that he ordered the chemical attack and would not confirm nor deny to CBS’s Charlie Rose in a 2013 interview that Syria had chemical weapons in its possession.
In 2014, under order from the Organization for the Prohibition of Chemical Weapons (OPCW), Assad agreed to destroy chemical stockpiles they had found, including sarin.
In a 2015 interview with "60 Minutes," Assad was asked under what circumstances would he step down from the presidency.
"When I don't have the public support," Assad said. "When I don't represent the Syrian interests and values."