TEL AVIV — The news came in a brief announcement on Thursday from the Israeli prime minister’s office: a watch belonging to a legendary Israeli spy had been recovered in a secret operation and brought back to Israel.

The watch belonged to Eli Cohen, whose spying in Syria is credited with helping Israel to a quick victory in the 1967 war, long after he had been caught and executed by the Syrian government.

Prime Minister Benjamin Netanyahu praised the “determined and courageous action” of the Israeli spy agency, Mossad, for returning “a memory from a heroic fighter who contributed greatly to the security of the state.”

But the announcement was tantalizingly short on specifics, setting off a buzz across Israel. Mr. Cohen was a national hero, with streets and buildings named after him and ceremonies honoring his memory every year. But had the Mossad, as Mr. Netanyahu implied, carried out a secret operation to recover a wristwatch?