What comes next after “Assad must go”?

President Barack Obama publicly called on Syrian President Bashar al-Assad to step down from power today, officially ending the U.S. effort to work with the Syrian government and beginning a new push for isolation and pressure on the embattled regime.

"The future of Syria must be determined by its people, but President Bashar al-Assad is standing in their way," Obama said in e-mailed statement this morning. "His calls for dialogue and reform have rung hollow while he is imprisoning, torturing, and slaughtering his own people. We have consistently said that President Assad must lead a democratic transition or get out of the way. He has not led. For the sake of the Syrian people, the time has come for President Assad to step aside."

Obama emphasized that the United States will not impose any solution on Syria, but will rather support the Syrian people’s demand for a transition through democratic means by applying increasing pressure on the regime and its allies. To that end, he issued a new executive order that requires the immediate freeze of all Syrian government assets that fall in U.S. jurisdiction, and prohibited U.S. citizens from doing any business with the Syrian government. The new sanctions also ban the import of Syrian petroleum products from entering the United States, and ban Americans from doing business with Syrian petroleum companies.

Secretary of State Hillary Clinton took to the podium this morning to emphasize the multilateral emphasis of the administration’s latest policy.

"As we increase pressure on the Assad regime to disrupt its ability to finance its campaign of violence, we will take steps to mitigate any unintended effects of the sanctions on the Syrian people," she said. "We will also continue to work with the international community, because if the Syrian people are to achieve their goals, other nations will have to provide support and take actions as well."

Many in Washington had been expecting the administration to call on Assad to leave power last week, but U.S. officials explained today that more time was needed to get other countries on the same page. The White House also distributed today statements from Canadian Prime Minister Stephen Harper, EU High Representative Catherine Ashton, and a trilateral joint statement from British Prime Minister David Cameron, French  President Nicolas Sarkozy, and German Chancellor Angela Merkel calling for Assad’s departure.

On a conference call with reporters today, three senior administration officials said that the administration began in earnest to prepare this announcement at the beginning of August. That date, which also corresponded with the beginning of Ramadan, was when an increase in regime violence "made it perfectly clear to everybody that his promises for reform were a lie and we had lost patience with him," as one official put it.

"The timing was driven by the horrific brutality of the Assad regime as well as the effort to build an international coalition to join us in our call for Assad to go today," the official said.

Obama discussed the situation in Syria with Turkish Prime Minister Recep Tayyip Erdogan on Aug. 11, and then had final conversations with several European leaders, including Cameron, on Aug. 13.

Meanwhile, U.S. Ambassador to Syria Robert Ford has still been in contact with the Syrian regime, holding conversations with senior Syrian Foreign Ministry officials as recently as last week, one official said.

So what comes next? The basic plan is to encourage European countries to similarly cut off their relationships with the Syrian energy sector. One official estimated that 90 percent of Syrian oil goes to Europe.

"We can’t predict how long this transition will take, nothing about it will likely be easy. But we’re certain that Assad is on his way out, we’re certain that international pressures will continue to build, we’re certain that his isolation will continue to increase," one official said. "We are going to be working with our allies and partners so that they can take additional actions on additional sanctions… so we expect there to be additional pressures brought to bear by our allies."

But none of the officials would predict when the Assad regime might fall.

"We expect there to continue to be struggle and sacrifice by the Syrian people," said another official. "But in that context, Bashar Assad is on his way out. That’s our assessment. The Syrian people will not accept his rule anymore."

The Cable asked the administration officials if they had taken the option of military action to protect civilians, as was used in Libya, off the table for Syria.

"I don’t think anybody believes that is the desired course in Syria," one official responded. "And so the simplest way to bring this to a conclusion is for the Syrian people to get the democratic transition that they deserve and that they are demanding."