Western nations stepped up demands for U.N. measures against President Bashar Assad after the Syrian leader ignored repeated calls for an end to the bloodshed in his country.

But U.N. Security Council battlelines were drawn when Russia's U.N. envoy said calls for sanctions did not help end the crackdown by Syrian security forces in which rights groups say more than 2,000 civilians have died.

U.S. President Barack Obama on Wednesday remembered the dead of the "awful" September 11 attacks in 2001, including Muslim Americans, as he marked the holy month of Ramadan at an Iftar dinner.

The president launched what will be a solemn series of events to mark the 10th anniversary of the attacks by al-Qaida operatives using hijacked airliners on U.S. centers of power in New York and Washington.

The United States Wednesday again stopped short of explicitly calling for Syrian President Bashar al-Assad to leave power, but said it would help his people achieve "dignity and freedom."

Washington further stiffened its stance, after a crackdown on protesters which has killed 2,000 people, by unveiling new sanctions on the state-owned Commercial Bank of Syria, the country's largest commercial bank.

The Obama administration is preparing to explicitly demand the departure of Syrian President Bashar Assad and hit his regime with tough new sanctions, U.S. officials said Tuesday as the State Department signaled for the first time that American efforts to engage the government are finally over.

The White House is expected to lay out the tougher line by the end of this week, possibly on Thursday, according to officials who said the move will be a direct response to Assad's decision to step up the ruthlessness of the crackdown against pro-reform demonstrators by sending tanks into opposition hotbeds.

President Barack Obama and his Republican foes clashed Monday on whether a new congressional "super committee" could even look at raising taxes as it works to rein in runaway deficits by $1.2 trillion.

The confrontation stoked concerns that the panel, created in the hard-fought debt-limit deal Obama signed into law last week, is doomed to deadlock even before leaders of the polarized House and Senate name its 12 members.

Syrian President Bashar Assad will forfeit legitimacy if his regime continues to carry out acts of violence against demonstrators in his country, the German government warned on Monday.

"If President Assad maintains his refusal to engage in dialogue with the Syrian people and continues to resort to violence, the German government will consider he has forfeited his legitimacy in further overseeing the fate of his country," deputy government spokesman Christoph Steegmans told a regular press conference.

The United States has vowed to "stay the course" in Afghanistan after 30 U.S. soldiers were killed there when, according to local officials, the Taliban shot down their helicopter.

The pledge from U.S. Defense Secretary Leon Panetta -- and a salute from President Barack Obama -- came Saturday, after the US troops, an interpreter and seven Afghan soldiers were killed during an anti-Taliban operation late Friday.

U.S. President Barack Obama on Saturday hailed the "extraordinary sacrifices" made by the 31 U.S. soldiers killed in Afghanistan when, according to local officials, the Taliban shot down their helicopter.

Obama also paid tribute to the seven Afghan soldiers killed during an anti-Taliban operation late Friday when a rocket fired by the insurgents struck their Chinook helicopter in Wardak province, southwest of the capital Kabul.

The Obama administration sent its ambassador back to Damascus on Thursday as it incrementally turned up the heat on Syrian President Bashar Assad with tougher rhetoric and new sanctions.

The White House said Assad's deadly crackdown on protesters had put Syria and the Middle East on a "very dangerous path," as Washington extended a raft of recent sanctions to include a businessman close to Assad and his family.

Syrian dissidents on Tuesday urged U.S. President Barack Obama to call on Syrian leader Bashar al-Assad to quit power and to press for U.N. sanctions over his regime's deadly crackdown on protests.

The demands -- presented in a first meeting between U.S. Secretary Clinton and members of Syria's disparate opposition -- added to U.S. domestic pressure on the Obama administration to take a tougher line against Assad's regime.