The Israeli military has said it destroyed an attack tunnel built by the Hamas militant group that stretched from the Gaza Strip into Egypt.
Military spokesman Lieutenant Colonel Jonathan Conricus said the mile-long tunnel ran underneath the Kerem Shalom border crossing, Gaza's main point of entry for humanitarian aid.
He said Israeli jets struck part of the tunnel and a new set of sophisticated "tools" destroyed the rest. There were no casualties.
Lt Col Conricus said forces had been monitoring its construction for some time and an imminent attack on Israelis was possible. The crossing has been closed until further notice.
Israel has made neutralising the tunnel threat a top priority since its 2014 war, when Hamas militants on several occasions made their way into Israel.
Although they did not manage to reach civilian areas, the infiltrations caught Israel off guard, killing five soldiers in one attack, and terrified the local population.
Sunday's operation marked the third such tunnel Israel has destroyed over the past two months.
But Lt Col Conricus said this did not mark "more of the same" since it involved the most advanced technological means Israel has deployed.
"(We) now hold a method, an organised system to destroy terror tunnels dug into Israel," he said.
He said the tunnel's route stretched underneath the Kerem Shalom crossing, where 15 million tons of food, clothing, construction material and other essential goods had been transferred into Gaza since the 2014 war.
Israel and Egypt have maintained a crippling blockade on Gaza since Hamas seized power in 2007.
Lt Col Conricus said the crossing itself was a potential target, as well as gas and fuel pipelines. The tunnel could have also been used to transfer militants and arms for attacks in Israel or Egypt's Sinai Peninsula, he said.
"It was a terror tunnel designed to strike strategic Israel assets," he said.
He did not specify which tools were used, but in the past Israel has said its new system involves combat units, military intelligence, logistics and research to destroy the tunnels.
Hamas initially said a typical smuggling tunnel was destroyed.
Prime Minister Benjamin Netanyahu said: "We are responding to aggression against the state of Israel and are taking vigorous and systematic action against hostile infrastructures."
Defence minister Avigdor Lieberman said the tunnel's construction was a clear violation of Israeli sovereignty and destroying it delivered a stinging blow to one of Hamas' most significant assets.
"The message to Gaza's leadership and residents is clear - invest in the sanctity of life and not these burial tunnels," he said.