Protesters march past a billboard with pictures of al-Khalifa family in Manama. (Joseph Eid/AFP/Getty Images)
The tiny Persian Gulf country of Bahrain is ruled by a 200-year-old Sunni monarchy. The al-Khalifa family is currently in charge, including King Hamad bin Isa al-Khalifa, his son and heir apparent Crown Prince Salman bin Hamad al-Khalifa, and Prime Minister Khalifa bin Salman al-Khalifa.
In February protests began in Bahrain, inspired by Tunisia and Egypt's successful overthrow of their leaders. The mainly Shiite population is seeking more access to resources and opportunities, and many want the royal family removed.
Saudi Arabia and other Gulf states sent in 1,500 troops to assist Bahraini forces in their crackdown. The government imposed a state of emergency on March 15 -- which recently expired -- and has arrested hundreds of protesters, political leaders and Shiite doctors and lawyers, who now are being tried in a special security court set up under martial law.
The NewsHour reported from Bahrain on the security crackdown.
Syrian President Bashar Assad in 2010 in Damascus, Syria (Sasha Mordovets/Getty Images)
Bashar Assad became president of Syria, a country of 22.5 million people, in 2000 after the death of his father Hafez, who ruled the Middle Eastern nation for 29 years.
Assad studied ophthalmology in London and later joined the Syrian army, where he became a colonel, before taking over for his father.
Anti-government protests erupted in March in the southern city of Daraa and rapidly spread elsewhere. Security forces reportedly have used tanks and live ammunition to squelch the protests.
Despite certain concessions -- including the lifting of the country's emergency law, which had been in place for 48 years -- demonstrators still want Bashar to leave office, but he has so far refused.
Yemeni President Ali Abdullah Saleh in Sanaa in April 2011. (Mohammed Huwais/AFP/Getty Images)
Ali Abdullah Saleh has been in power in Yemen for nearly 33 years, and is facing protests that threaten to tip the country of 24 million into civil war.
Saleh was elected president by parliament in October 1994, then directly elected president in September 1999 with 96 percent of the vote, according to Reuters. He was re-elected in September 2006 to a seven-year term.
Protests over his leadership, high unemployment and corruption began in late January and gained steam over the next couple of months.
Saleh has backed away from an Arab Gulf agreement to step down in exchange for immunity from prosecution. And ensuing clashes between security forces and members of the opposition forces seeking his removal have left dozens dead and wounded.
Libyan President Moammar Gadhafi in 2004 in Tripoli. (Pascal Le Segretain/Getty Images)
Moammar Gadhafi took power in Libya in a bloodless military coup on Sept. 1, 1969 at the age of 27. His alleged ties to international terrorism isolated the country diplomatically.
But in 2003, Gadhafi denounced terrorism, accepted responsibility for the Lockerbie bombing, and agreed to dismantle the country's weapons of mass destruction programs, leading to the lifting of U.N. sanctions and the normalizing of relations with the U.S.
In February, an armed rebellion began against Gadhafi. NATO forces got involved in March, bombing Libya's air forces and ammunition sites after the U.N. Security Council authorized a no-fly zone over Libya in order to protect its civilians.
But the fighting in the North African nation of 6.6 million has continued.