The New York Times quoted Israeli military and intelligence officials as saying that a large number of the weapons used by the Islamic Resistance Movement (Hamas) in the attacks of last October 7 came from an unexpected source, which is the Israeli army itself.

For years, analysts have pointed to underground smuggling routes to explain how Hamas remained so heavily armed despite Israel's military blockade of the Gaza Strip.

But recent intelligence information has shown the extent to which Hamas is able to build many of its missiles and anti-tank weapons from thousands of munitions that did not explode when Israel fired them into Gaza, according to Israeli and Western weapons and intelligence experts. The movement also arms its fighters with weapons taken from Israeli military bases.

Intelligence surveyed by The New York Times during months of fighting revealed that just as the Israeli authorities misjudged Hamas' intentions before October 7, they also underestimated its ability to obtain weapons.

The newspaper points out that what is clear now is that the same weapons that Israeli forces used to impose the siege on Gaza over the past 17 years are now being used against them.

It quoted Michael Kardash, former deputy head of the bomb disposal department in the Israeli National Police and an advisor to the Israeli police, saying, “Unexploded ordnance is the main source of explosives for Hamas.”

Weapons experts say that approximately 10% of munitions usually do not explode, but in the case of Israel the number may be higher. An Israeli intelligence officer - who spoke to the newspaper on the condition of anonymity - said that the failure rate of some of these missiles could reach 15 percent. %.

Israel's arsenal includes Vietnam-era missiles, which the United States and other military powers have long since discontinued.

Either way, years of intermittent bombardment and the recent shelling of Gaza have left thousands of tons of unexploded ordnance scattered in the area awaiting reuse, and a single 750-pound bomb that fails to explode can turn into hundreds of rockets.

Israeli officials knew before last October's attacks that Hamas was capable of making use of some Israeli-made weapons, but the scope astonished weapons experts and diplomats alike.

The Israeli authorities also knew that their weapons depots were vulnerable to theft.

A military report issued early last year indicated that thousands of bullets and hundreds of weapons and grenades had been seized by Hamas from poorly guarded bases.

The newspaper reported that after Hamas breached the border in Operation Al-Aqsa Flood on October 7, 4 Israeli soldiers discovered the body of a Hamas gunman who was killed outside the Ra’im military base. One of the soldiers said that Hebrew writing was visible on a hand grenade on his belt, and he identified it as a bomb. A modern Israeli bulletproof device.

Other Hamas fighters also seized some weapons from the base and carried them to Gaza, Israeli military officials say.

The newspaper's report indicated that members of an Israeli forensic team collected one of the 5,000 rockets fired by Hamas that day, and by examining the rocket, they discovered that its military explosives most likely came from an unexploded Israeli rocket fired at Gaza during a previous war, according to an Israeli intelligence officer.

If the attacks of last October 7 showed the combined arsenal that Hamas had gathered together, as the newspaper says - which included Iranian-made attack drones and North Korean-made missile launchers, the types of weapons that Hamas is known to smuggle into Gaza through tunnels - Other weapons, such as anti-tank explosives, RPG warheads, thermobaric bombs, and explosive devices, have been repurposed as Israeli weapons, according to videos published by Hamas and remnants uncovered by Israel.

Rockets and missiles require huge amounts of explosive material, which officials say is the most difficult material to smuggle into Gaza.