Jerusalem - Israel said on Monday it had used a “breakthrough” technique to unearth a 40-metre-(132-foot)-deep cross-border tunnel dug by Hamas militants from Gaza, the first such discovery since the 2014 war, but played down any prospects of renewed conflict.

Since being blindsided by Hamas tunnel raiders during the war, Israel has, with U.S. help, stepped up work on technologies for spotting the secret passages. Some Israelis who live on the Gaza frontier believe militants are digging fresh tunnels and worry the counter-measures will come too late.

Video of the tunnel was released to the media Monday afternoon and document the structure’s contours.

The tunnel made public on Monday was discovered days earlier but kept under wraps by Israel as it probed what it said were hundreds of meters (yards) of shafts on the Israeli side of the border along the southeast of the Gaza Strip. The network was then razed.

Prime Minister Benjamin Netanyahu credited “a world-first breakthrough in tunnel-locating capabilities” for the find but indicated more work was need to complete the counter-measure.

“I congratulate the IDF Chief-of-Staff, the IDF, the ISA and the intelligence and technology personnel on this unique breakthrough. The government is investing considerable capital in countering the tunnel threat. This is an ongoing effort that will not end overnight. We are investing in this and will continue to do so with determination”, he said in a TV statement.

Commentary on Israel’s Army Radio said the effectiveness of the system announced by Netanyahu should be gauged only once several more tunnels are discovered.

View of a tunnel detected by the IDF meant for attacking Israel reaching from the southern part of the Gaza Strip into Israeli territory. April 18, 2016. Photo by IDF Spokesperson/FLASH90View of a tunnel detected by the IDF meant for attacking Israel reaching from the southern part of the Gaza Strip into Israeli territory. April 18, 2016. Photo by IDF Spokesperson/FLASH90

An Israeli military spokesman, Lieutenant-Colonel Peter Lerner, said the tunnel was mostly built after the Gaza war, during which 12 soldiers were killed by Hamas gunmen who burrowed across the border on four occasions.

Hamas’s armed wing, which has largely held fire since the war, implicitly claimed the tunnel as its own and said it was “only a drop in the sea of what the resistance has prepared”.

Israel has signaled the mere existence of a tunnel - as opposed to its use for an attack - may not be a casus belli.

“We do not seek conflict, but if Hamas tries to provoke the State of Israel and disrupt the lives of residents of the Gaza periphery communities, it will be dealt a very strong blow,” Defence Minister Moshe Yaalon said in a statement on Monday.

The Gaza war killed more than 2,100 Palestinians and devastated parts of the enclave. Gaza medical sources and U.N. officials say most were civilians, a figure disputed by Israel, which lost 67 troops and six civilians to the fighting.

The Gaza periphery is now mostly quiet, except for occasional Palestinian rocket attacks Israel says were carried out by Islamist groups that view Hamas as too lenient.

Israeli security sources say a half-dozen classified anti-tunnel technologies have long been under development though held up by funding problems that were partly alleviated by a U.S. research grant of $40 million this year.

View of a tunnel detected by the IDF meant for attacking Israel reaching from the southern part of the Gaza Strip into Israeli territory. April 18, 2016. Photo by IDF Spokesperson/FLASH90View of a tunnel detected by the IDF meant for attacking Israel reaching from the southern part of the Gaza Strip into Israeli territory. April 18, 2016. Photo by IDF Spokesperson/FLASH90

A drill is seen on the Israeli side of the Southern Gaza border where, according to the Israeli army, a tunnel was discovered, Israel April 18, 2016. REUTERS/Amir CohenA drill is seen on the Israeli side of the Southern Gaza border where, according to the Israeli army, a tunnel was discovered, Israel April 18, 2016. REUTERS/Amir Cohen