Revenues from oil and gas exports, which account for up to a third of state revenues and are the single biggest source of foreign currency, will dry up at the beginning of November, when a European Union ban on imports will fully come into force.

The unrest has paralyzed the tourism industry, which brings in $7.7 billion a year. Several hotels in Damascus said they did not have any bookings for now or anytime in the future, and some hotel owners said that they closed down in the summer because they could no longer afford to pay salaries and bills.

An owner of a small candy shop in Souk al-Hamidiyeh, an old market in the heart of Damascus, said that he had not seen a single tourist since March, when the uprising against Mr. Assad began.

“And it doesn’t look like we will see tourists anytime soon,” the owner added.

Dik al-Jin, one of the oldest restaurants and the most popular site for weddings and parties in Homs, a city in central Syria where the uprising has the semblance of a civil war, also shut down because of a lack of customers, soon after the demonstrations broke out.

But uncertainties persist over the international strategy to put pressure on the Syrian economy. American and European officials have debated whether the sanctions will end up hurting average Syrians more than the leadership. Some analysts have contended that the government may try to paint itself as a victim and court support by casting the sanctions as a contest of “us against them.”

Indeed, in the 1990s in Iraq, which was hit by comprehensive sanctions, popular anger was often directed at the United Nations and the West, not the government of Saddam Hussein.

For now, and in spite of the fraying economy, the government seems buoyed by a sense of confidence over having blunted some of the mass protests this summer in cities like Hama and Deir al-Zour. Syrian officials also have faced sanctions before, only to weather them and seek to rehabilitate themselves once conditions in the region shift. Syrian officials also received a lift when China and Russia vetoed a resolution in the United Nations Security Council that condemned the violent oppression of antigovernment demonstrators last week.