JERUSALEM — No sooner had the Israeli military excavators begun to drill into the rocky ground than the suspicions burst forth.

They were not directed so much at Hezbollah, Israel’s archenemy to the north: Few Israelis were completely surprised at their government’s assertion that the group had dug tunnels under the Lebanese border. Residents there have complained of strange sounds at night for years.

Instead, the distrust was directed at Prime Minister Benjamin Netanyahu of Israel, who recently assumed the additional role of defense minister, and who is facing increasing legal woes. The military operation to expose and destroy what his government described as tunnels into Israeli territory began two days after the Israeli police recommended that Mr. Netanyahu be indicted on bribery, fraud and other charges — the third corruption case against him and potentially the most damaging.

At the same time, Mr. Netanyahu is trying to preserve his fragile coalition amid accusations that he has not been tough enough in handling the simmering conflict with Gaza to the south. He and his political opponents are now in an election year.