BEIRUT, Lebanon — The fortunes of President Bashar al-Assad have suffered over the past two months, with battlefield setbacks and new signs of doubt emerging within his political base, as the civil war in Syria drags on with no end in sight.

Now, though, he and his inner circle believe they have been granted a reprieve — at least politically — by President Obama’s declaration that he may strike in Syria against the extremist group the Islamic State in Iraq and Syria, according to analysts and allies of the Syrian government who say they are in contact with officials in Damascus.

To Mr. Assad and his closest advisers, these people say, the American decision represents a victory for his longstanding strategy: obliterating any moderate opposition to his rule and persuading the world it faces a stark choice between him and Islamist militants who threaten the West.

But there are also worries in Damascus that the potential American strikes in Syria, part of a ramped-up campaign against ISIS, carry new risks. Pro-government analysts say that Syrian officials are unsure who would benefit militarily — government forces, or Syrian insurgents and separatist Kurds, who have also clashed with the foreign-led ISIS militants.