The difficulty in understanding what America is trying to do in Syria has persisted in the current debate over how to respond to the Assad government's alleged use of chemical weapons.
Threatening military reprisals, Obama said that the "United States military doesn't do pinpricks" only a day after Secretary of State John Kerry promised an "unbelievably small" operation.
In the last few days Obama has turned again to help from Russia, a Syrian ally the U.S. repeatedly has accused of being complicit in the Assad government's wartime atrocities.
A look at how U.S. policy in Syria has evolved:
THE END OF ENGAGEMENT
Arab Spring-inspired demonstrations erupt across Syria in March 2011. The unrest comes as the Obama administration is hoping to coax Assad into ending Syria's alliance with Iran and support for militant groups Hamas and Hezbollah. As the protests spread and reprisals worsen, U.S. engagement narrows to trying to get the Syrian government to respect political opponents and move toward democracy.
Then-Secretary of State Hillary Rodham Clinton says Assad is seen by some U.S. lawmakers as a "reformer." Days earlier, Kerry, then a U.S. senator, argues that Syria is poised for change "as it embraces a legitimate relationship with the United States and the West." The administration resists calls over the next months to recall the U.S. ambassador, the first senior American posted to Damascus in five years. Obama reacts to increased brutality by Assad's forces in April by ordering a new set of sanctions against Syria. Violence escalates, with Assad sending tanks into cities throughout the summer. Citizens and defecting soldiers take up arms against government. By August, Obama publicly calls on Assad to resign.
REBUFFED AT THE U.N.
The U.S. and allies take their case to the United Nations in October 2011, asking the Security Council to condemn human rights violations in Syria and demand an end to violence. Russia and China veto the resolution. That month, the U.S. pulls Ambassador Robert Ford out of Damascus because of security concerns. Ford returns in December, then leaves for good two months later. The U.S. tries anew at the U.N. in February 2012, backing an Arab-proposed plan to hold Syrian human rights violators accountable. Russia and China again exercise their veto.
The U.S. turns to Arab and European allies and convenes the first "Friends of Syria" conference in Tunisia to seek ways to support Syria's opposition. U.S. intelligence officials start warning about al-Qaida and other extremist militants joining the fray. Still hopeful of finding a peaceful resolution, the U.S. urges that no one send weapons to either side. The violence worsens. In March 2012, Obama pledges "nonlethal" aid to the rebels. The U.N. says about 8,000 are dead after a year of violence.
FALSE DIPLOMATIC HOPE
Secretary of State Clinton believes she secures Russia's commitment on a path forward in June 2012 with the "Geneva process." It calls for a Syrian transitional government through negotiation between Assad's government and the opposition.
Within hours of signing on to the strategy, the U.S. and Russia bicker over whether the agreement includes Assad relinquishing power. Russia and China veto a third U.N. resolution in July after the U.S. and its allies try to make the agreement enforceable. The process fizzles out without delivering peace talks.
Arab governments disregard the U.S. call for a weapons embargo and supply the rebels with increasingly advanced weaponry. Obama rebuffs suggestions by Clinton, CIA Director David Petraeus and other senior U.S. officials to provide weapons to moderate opposition forces. By July, the U.N. says 5,000 Syrians are dying each month in the fighting.
RED LINE
Responding to worrying intelligence indications, Obama declares in August 2012 that the use or deployment of the Syrian government's chemical weapons stockpiles is a "red line," which if crossed would change America's calculus in the conflict.
Rebel military advances stall. At the behest of Washington and others, the Islamist-dominated political opposition reforms itself in November 2012 to include more moderates and minorities. The U.N. puts the death toll since the beginning of the conflict at 60,000. In December, the U.S. recognizes the Syrian Opposition Coalition as the Syrian people's legitimate representative. U.S. humanitarian aid increases significantly. Washington also puts one rebel faction, the al-Qaida-linked Nusra Front, on the U.S. terrorism blacklist.
NEW ASSERTIVENESS
Obama starts his second term as president and Kerry replaces Clinton as secretary of state. The U.S. becomes more assertive in its rhetoric about shifting the Syrian civil war's momentum and trying to convince Assad that he cannot prevail militarily and should relinquish power.
In February 2013, the U.S. decides to send medical kits, food and other forms of nonlethal aid directly to the rebels but refuses to join its Arab partners in sending weapons. In March, Syrian rebels and Assad's government accuse each other of using chemical weapons. The U.S. begins investigating. In May, Kerry travels to Moscow and revives the Geneva peace process. U.S. and Russian officials again differ on whether Assad must relinquish power. Like its predecessor, the "Geneva II" effort delivers no progress.
CHEMICAL WARFARE
U.S. intelligence concludes in June that Assad's forces used small amounts of the nerve agent sarin in several attacks. Obama responds by authorizing the delivery of lethal aid to Syria's rebels, but no weapons or ammunition are sent.
Military officials express increasingly dire assessments of the role al-Qaida and other terrorist groups are playing in Syria and the options available for U.S. military intervention. By July, the U.N. secretary-general says more than 100,000 people have died. The war takes an even more ominous turn on Aug. 21 with a massive chemical weapons attack outside Damascus. Within days, the U.S. declares with "high confidence" that Assad's forces are responsible and says more than 1,400 people, including more than 400 children, were killed.
RED LINE CROSSED
Obama and top aides threaten limited military action. Four U.S. destroyers equipped with cruise missiles are put on standby in the eastern Mediterranean Sea.
The Parliament in Britain, America's closest military partner, rejects using force in an Aug. 29 vote and U.S. officials raise the possibility of a unilateral American attack. Two days later, Obama asks Congress for official authorization to strike. Encountering resistance, the president and his advisers say he can act even if Congress rejects his request.
PRESIDENT REBUFFED
Democrats and Republicans in the House and Senate increasingly voice opposition to Obama's strategy. Obama meets Russian President Vladimir Putin on the sidelines of a global economic summit on Sept. 6 and they discuss diplomatic alternatives to get Assad to surrender his chemical weapons stockpiles.
Obama asks Senate leaders on Sept. 9 to delay voting on authorizing military action. He addresses the nation on Sept. 10 and tries to persuade Americans to support military action in Syria if diplomacy fails. Assad's government announces its intention to sign the U.N. treaty banning chemical weapons and hand over its stockpiles. Diplomatic wrangling continues between the U.S. and Russia over how to verify that Syria lives up to the deal in a timely manner and what consequences it should face if it doesn't. U.S. officials say the Syrian rebels have received a first package of U.S. lethal aid.
