After the United States and other major powers called for Syrian President Bashar al-Assad to step down, senior Obama administration officials spoke with reporters about the significant change in approach.
Officials say the coordinated actions were the culmination of months of steadily increased pressure on the Syrian leader, including statements condemning the use of violence against civilians, and calls for President Bashar al-Assad to lead a democratic transition or get out of the way.
President Barack Obama discussed the Syria situation, including a rise in violence during the Muslim Holy Month of Ramadan, with German Chancellor Angela Merkel and French President Nicolas Sarkozy.
They said Obama and British Prime Minister David Cameron agreed in a conversation on August 13 that more aggressive actions were needed.
At the same time there were close consultations with key regional players, including Turkey's Prime Minister Erdogan, and with key Arab allies such as Saudi Arabia and others in the Gulf Cooperation Council.
A senior administration official called the U.S. partnership with Turkey regarding Syria extremely important, given Turkey's long-standing relationship with Syria's government, adding the two countries will remain in close touch going forward.
Officials addressed a number of questions from reporters after the calls by the United States, Britain, France, Germany, Canada, and the European Union for President Assad to leave power, including what the United States and allies would do if the latest steps do not bring about his departure.
The officials said President Obama's executive order is designed to choke off additional resources the Syrian government could use to extend its crackdown on civilians, and deepen the international isolation of Syria's leadership.
Secretary of State Hillary Clinton spoke about actions being taken. "His Executive Order immediately freezes all assets of the government of Syria that are subject to American jurisdiction, and prohibits American citizens from engaging in any transactions with the government of Syria or investing in that country," she said.
Officials also responded to a question about the comparison between Syria and President Obama's handling of political upheaval in Egypt earlier this year, with one reporter noting Obama's fairly rapid call last February for former President Hosni Mubarak to step down.
Asked whether the option of military action was being removed from the table, an official said he did not think anybody views this as the "desired course". The simplest way to move to a democratic transition, the official added, is for President Assad to step aside.
One official said the U.S. response to the so-called Arab Spring has been consistent - condemning violence, upholding universal rights and calling for political and economic reforms - but the United States recognized that each country would change in its own way.
The official said relationships that could be used as leverage differed in each country, noting that in Egypt the United States was able to issue an early statement for Mubarak to leave power, and had close contacts with Egyptian counterparts on how they responded to events.
Obama administration officials also commented on what impact a potential Assad departure could have on Syria's role in the Arab-Israeli peace process.
Saying the U.S. remains committed broadly-speaking to the peace process but has no investment in any individual's particular involvement in it, one official said President Assad's ability to be at all a figure in that are "long gone."