Israel on Tuesday began to destroy Hezbollah tunnels dug under its northern border, an operation launched with much fanfare at a time when the country’s embattled Prime Minister Benjamin Netanyahu faces a corruption investigation and criticism for being soft on security.

The military said it had exposed one of the Lebanese militant group’s tunnels that crossed into Israeli territory in what it dubbed “Operation Northern Shield.” Military spokesman Lt. Col. Jonathan Conricus said that “several” tunnels had been monitored for “quite a long period of time” and the operation had been planned for a year and a half.

“Anyone who tries to harm the State of Israel will pay a heavy price,” Netanyahu said in a statement. He said that he had briefed Secretary of State Mike Pompeo on the situation during a meeting in Brussels on Monday night explaining that the tunnels are a “flagrant violation” of Israeli sovereignty and U.N. resolution 1701.

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