Israel launched an operation Tuesday to destroy tunnels it said Hezbollah had dug under its northern border, announcing the move with much fanfare at a time when Prime Minister Benjamin Netanyahu faces multiple corruption investigations as well as accusations of being soft on security. 

The military said it had exposed one of the Lebanese militant group’s tunnels into Israeli territory in a mission it dubbed “Operation Northern Shield.” A spokesman, Lt. Col. Jonathan Conricus, said the tunnel began in a house in Lebanon and extended more than 40 yards into Israel. 

Netanyahu said in a televised address Tuesday night that the tunnels were built by Hezbollah but funded by Iran.

“They were built with one purpose in mind — to attack and murder innocent Israeli men, women and children. This is a grave violation of Israel’s sovereignty and a gross violation of U.N. Security Council Resolution 1701,” he said. The resolution, which Lebanon also says Israel routinely breaches by violating its airspace, dates to the end of the 2006 war between Israel and Hezbollah.

Netanyahu said Lebanon would be held responsible for “all terror activity” emanating from its territory and urged the U.N. Security Council and countries around the world to condemn the group’s actions. Israel would defend itself against Iran’s attempts to entrench itself in Syria, Lebanon and Gaza, he said.

Tuesday’s development comes amid deep concern about the buildup of Iranian proxies in Syria in recent years. In the past few days, there has also been a renewed focus on Lebanon, after allegations that a plane carrying Iranian weapons for Hezbollah, its most powerful proxy, had arrived at Beirut’s airport. 

However, the dramatic announcement of the operation — which has so far involved the unearthing of one tunnel that appears to have been monitored by Israel for several years — triggered concern that domestic politics were at play. 

Netanyahu’s security credentials have taken a knock in recent weeks. He faced widespread criticism, including from within his coalition, for agreeing to a cease-fire with Hamas after the militant group that runs the Gaza Strip fired more than 450 rockets and mortar rounds into Israel following a botched Israeli raid into Gaza. 

He had earlier agreed to allow Qatar to send money to Gaza to pay the salaries of civil servants and alleviate the humanitarian crisis there. 

Those events led to the resignation of his right-wing defense minister, Avigdor Liberman, and left his ruling coalition hanging by a thread, with a one-seat majority in the Knesset, or parliament. Protests were held in Israeli communities in the vicinity of Gaza. 

Education Minister Naftali Bennett also briefly threatened to resign and pull his party out of the coalition, which would topple the government, if he were not given the defense portfolio, saying he would work to restore Israel’s military strength. 

Netanyahu, who did not bend and instead appointed himself defense minister, has since continued to be dogged by corruption allegations. On Sunday, Israeli police recommended indicting him on charges of corruption and bribery in one of three criminal investigations into his conduct.

“We’re clearly hearing some form of domestic political messaging,” said Michael Horowitz, a senior analyst at the Middle ­East-based security consultancy Le Beck International. “Israel has known about these tunnels for years, and while the timing also makes sense regionally, it certainly helps Netanyahu turn the page of the recent confrontation in Gaza that almost brought the Israeli government down.”

Israel is also trying to send a message of deterrence to Hezbollah, he said, which as of Tuesday had not reacted to the news that Israel had uncovered one of its tunnels and plans to destroy more.

On Thursday, Israel warned Lebanon to stop allowing Iran to send weapons to Hezbollah after an Iranian cargo plane suspected of carrying a consignment landed in Beirut.

Hours later, Israel was accused of carrying out strikes inside Syria, which fired a barrage of antiaircraft rockets in response. Hezbollah then launched a campaign it dubbed “defend our skies,” accusing Israel of breaching Resolution 1701 by violating Lebanon’s airspace. It threatened to retaliate against any Israeli attack, releasing a video showing targets in Israel with their coordinates.

Iran’s regional hegemony has also been a driving foreign policy concern of the Trump administration. National security adviser John Bolton said Tuesday that the United States “strongly supports” Israel’s efforts to stop tunneling into its territory.

“More broadly, we call on Iran and all of its agents to stop their regional aggression and provocation, which pose an unacceptable threat to Israeli and regional security,” Bolton said.  

Conricus said the timing of Operation Northern Shield was guided by the “maturation of different capabilities that will allow us to feel confident enough to find the tunnels.” 

The army assembled a task force to assess the tunnel threat in the area in 2014, he said, and began preparing for the current operation more than a month ago.

“Several” tunnels were monitored for “quite a long period of time,” Conricus said.

But despite apparently being aware of the tunnels, Israel kept the information quiet.

Residents of northern Israel say that for two or three years they have heard sounds of drilling and knocking underground and had alerted the military. Conricus said engineering experts investigated every report. 

“We heard noises. We called the army. We also took pictures of Hezbollah operatives on the border,” Zamir Hatan, from the northern border village of Shtula, told Israeli Radio. “The army held a meeting with us and told us we had nothing to worry about and that as long as they weren’t shooting, there was nothing to be done.”

The military had also previously told journalists that the rocky terrain in the area meant it was not possible for Hezbollah to build tunnels. 

Israel has been using what it says is new technology to detect and destroy tunnels built by Hamas in the south, under the fence with Gaza. Those are normally destroyed before their existence is announced. 

Yoav Kish, a member of Netanyahu’s party and chairman of the Knesset’s Internal Affairs Committee, said the latest operation proves that what was seen as the prime minister being “hesitant and weak” in Gaza was actually “restraint” that made the move in the north possible.

“A tough military move against Hamas could have led to regional deterioration and confrontation in the north as well,” he said.

Liz Sly in Beirut contributed to this report.