President Bashar al-Assad of Syria is facing the most serious challenge to his rule since he came to power in 2000 following the death of his father, Hafez.
After taking office, Mr Assad sought to present himself as a reformer.
The country initially underwent a degree of political liberalisation, with hundreds of political prisoners being released, dissidents allowed to speak openly, and a few tentative steps towards easing media restrictions.
But the pace of change soon slowed - if not reversed - and subsequent years saw the creation of "liberalised authoritarianism" rather than democratic rule.
And when protests against the government began in March 2011, inspired by the uprisings in Tunisia and Egypt, orders were given to crush the dissent.
The brutal crackdown by Syria's security forces has not, however, stopped the uprising and many believe it is only a matter of time before President Assad is overthrown.
For Syria's security services and military, the ruling Baath Party, the massive state bureaucracies, and the dominant Alawite sect, Mr Assad represented stability and continuity when his father died after more than a quarter of a century in power.
However, Bashar al-Assad was not always destined for the highest office.
As second son, born on 11 September 1965, he had largely been left to follow his own interests. He studied at the Hurriya School in Damascus and at 14 joined the Baath Youth Movement.
He graduated from the University of Damascus with a degree in ophthalmology, intending to pursue a career in this field.
Between 1988 and 1992 he studied ophthalmology at Tishrin military hospital in Damascus, before going to London for further studies as an ophthalmologist.
After the death of his older brother, Basil, in a high-speed car crash in 1994, Mr Assad was hastily recalled from London and thrust into the spotlight.
He soon entered the military academy at Homs, north of Damascus, and rose through the ranks to become an army colonel in January 1999.
In the last years of his father's life, Mr Assad emerged as an advocate of modernisation and the internet, becoming president of the Syrian Computer Society.
He was also put in charge of a domestic anti-corruption drive, which reportedly resulted in prominent figures from the old leadership being put on trial.
Flirtation with reform
Following his father's death on 10 June 2000, Mr Assad's path to the presidency was assured by regime loyalists who removed the last remaining obstacles, such as amending the constitution to allow a 34 year old to become head of state.
He was then promoted to the rank of Field Marshal, and appointed commander of the armed forces and secretary general of the Baath Party.
A July 2000 referendum confirmed him as president with 97% of the vote.
In his inaugural address, Mr Assad promised wide-ranging reforms, including modernising the economy, fighting corruption and launching "our own democratic experience". He also pointed to the "dire need for constructive criticism".
It was not long before the authorities released hundreds of political prisoners and allowed the first independent newspapers for more than three decades to begin publishing. A group of intellectuals pressing for democratic reforms were even permitted to hold public political meetings and publish statements.
The "Damascus Spring", as it became known, was short-lived.
By early 2001, the intellectuals' meetings began to be closed down or refused licences and several leading opposition figures were arrested. Limits on the freedom of the press were also soon put back in place.
For the rest of the decade, emergency rule remained in effect. The many security agencies continued to detain people without arrest warrants and held them incommunicado for lengthy periods, while Islamists and Kurdish activists were frequently sentenced to long prison terms. Any economic liberalisation benefitted the elite and its allies, rather than creating opportunities for all.
Many analysts believe that reform under Mr Assad has been inhibited by the "old guard", members of the leadership loyal to his late father.
His family is also said to have played a role in encouraging him to suppress dissent, including his brother Maher, the head of the Republican Guard; his sister Bushra and her husband Asef Shawkat, deputy chief of staff of the armed forces; and his first cousin, Rami Makhlouf, arguably the most powerful economic figure in Syria.
In 2007, Mr Assad won another referendum with 97% of the vote, extending his term for another seven years.
In foreign policy, Bashar al-Assad continued his father's hard-line policy towards Israel. He has repeatedly said that there will be no peace unless occupied land was returned "in full", and continues to support militant groups such as Hamas and Hezbollah, although he has floated the idea of talks on the Golan Heights.
His vocal opposition to the 2003 US-led invasion of Iraq, and the Syrian authorities' tacit support of Iraqi insurgent groups, also prompted anger in Washington, but it was popular in Syria and in the wider region.
Syria's already tense ties with the US soured in the wake of the February 2005 assassination of Lebanon's former Prime Minister, Rafik Hariri.
The finger of suspicion was immediately pointed at President Assad, his inner circle and the Syrian security services, which dominated Lebanon. Despite their denials of involvement, international outrage at the killing forced Syrian troops to withdraw from Lebanon that April, ending a 29-year military presence.
A UN tribunal earlier this year charged four suspects, all connected to Hezbollah, in connection with the killing of Hariri.
In recent years, Mr Assad has built close ties with Iran as well as Russia and China. Relations with Turkey and France had also improved until the uprising began.
The United States only resumed full diplomatic relations with Syria last January, although its ambassador has been a vocal critic of the crackdown on dissent and was briefly withdrawn after threats to his safety were made.
When anti-government protests erupted in the southern city of Deraa in mid-March 2011, President Assad initially appeared to be unsure how to respond, but it was not long before only force was used to combat them.
In his first speech, two weeks after the first unrest, he insisted that questions of reform and economic grievances had been overshadowed by a small number of troublemakers and saboteurs who had sought to spread among Syrians, as part of an external conspiracy to undermine the country's stability and national unity.
Then in April - with the death toll at 200 - Mr Assad dismissed the cabinet and officially lifted the hated Emergency Law, which had been in place since 1963 and under which security forces detained and tortured people with impunity.
He also said there would be also be new legislation to dilute the monopoly of the Baath party, a new, modern press and media law, and a law which would regulate demonstrations, whereby protesters would be protected by police.
But days later, the crackdown against protesters was stepped up.
Over the next month, soldiers supported by tanks were sent into restive towns and cities, including Deraa, Baniyas, Homs, Hama and the suburbs of Damascus, to combat "armed criminal gangs". By mid-May, the death toll had reached 1,000.
Despite the security forces' concerted and ruthless efforts, and pledges by President Assad to free political prisoners and start a "national dialogue" on reform, the uprising continued unabated in almost every part of the country.
In August, with the death toll at 2,000, Mr Assad told state television that his government was in no danger of falling. He said the solution in Syria was a political one, but that violence should be dealt with firmly.
He also said opponents of the regime were increasingly resorting to violence, carrying out attacks on the military, the police and other security forces.
By early December the death toll had reached 4,000, Syria's security forces had lost control of large parts of the country and been accused by the UN of crimes against humanity, and sanctions were crippling the country's economy, but Mr Assad maintained a defiant tone in an interview with ABC News.
The president denied ordering the military to kill or be brutal in its crackdown on anti-government protesters, saying only a "crazy person" would kill his own people.
"There was no command, to kill or to be brutal," he said. "I don't own them, I am president, I don't own the country so they are not my forces."
"I did my best to protect the people, so I cannot feel guilty," he added.
"You feel sorry for the lives that [have] been lost. But you don't feel guilty - when you don't kill people."
Mr Assad also challenged the "false allegations" on which much of the media - and the UN Human Rights Commission - had based their conclusions about what was happening in Syria.