The Israeli government never acknowledges individual strikes, and the Syrian government and Hezbollah do not always acknowledge when they have been hit. But last August, Maj. Gen. Amir Eshel, the outgoing commander of the Israeli Air Force, acknowledged that Israel had launched nearly 100 strikes on convoys since 2012.

Monday’s strike came one day after President Trump called Mr. Assad an “animal” and warned him and his Russian and Iranian backers that they would have a “big price to pay” for the alleged chemical attack that killed dozens of people near Damascus on Saturday.

Russia did not respond immediately to the accusation, although a spokesman for President Vladimir V. Putin rejected Mr. Trump’s inflammatory language. “Assad is the legitimate president of the Syrian Arab Republic,” the spokesman, Dmitri S. Peskov, said. “It’s hardly acceptable to apply that sort of abusive wording to a president.”

Russia was also the first to contend that it was Israel that had carried out Monday’s airstrike, a departure from what analysts said was its previous policy of looking the other way when Israel hit Iranian assets in Syria.

“Moscow decided to be judge and jury — to side with Assad and Hezbollah, which were saying it was an Israeli attack, rather than siding with Israel in allowing Israel to maintain ambiguity,” said Mr. Zalzberg, the analyst.

The latest escalation comes at a pivotal time for the United States, as Mr. Trump charts the American course in Syria. He said last week that he wanted to withdraw the approximately 2,000 American troops based in eastern Syria, where they are fighting the jihadists of the Islamic State, but his vow to respond to the reported chemical attack risks pulling him into Syria in other ways. Some of his advisers believe that limiting Iranian ambitions is one reason the United States should maintain some military presence in Syria.

Despite Mr. Trump’s promise to respond to the chemical attack, which killed at least 49 people in the Damascus suburb of Douma, it remained unclear what he would do and how it would relate to a broader American policy toward Syria.