(Bloomberg) -- Besieged and degraded after more than a year of war, pockets of Hamas fighters in northern Gaza have been dogging the Israeli army with what are often makeshift munitions. That's precisely what their sponsors in Tehran intended.
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Fourteen pages of notes, interspersed with sketches of drone avionics and rocket nose-cones, provide a glimpse of what intelligence officers say has been secret training within Iran for Hamas members tasked with creating a homegrown arsenal.
As troops and tanks have churned through Gaza, cutting off weapons supply lines and penning in areas where insurgency still simmers, knowledge of how to improvise is especially valuable to the surviving Hamas fighters. It also makes it that much more difficult for the Israeli military to achieve one of its primary war aims -- removing Hamas from the Palestinian enclave.
"The weapons factories the Israelis have been destroying were based on Iranian know-how, but these are increasingly being destroyed," said Matthew Levitt, a counter-terrorism expert with the Washington Institute for Near East Policy. "The remaining Hamas fighters will use whatever weapons they can come by."
Iran and the Palestinian Islamist group have for years spoken openly about an alliance that encompassed funding and weapons smuggling. They've been more circumspect about other aspects of the relationship, which intelligence officers believe also included bringing Hamas members to Iran to be trained in arms manufacturing.
Israel saw the results of Iran's assistance to Hamas in October last year, when thousands of Palestinian fighters, backed by rocket barrages, surged into its southern towns and army bases, killing about 1,200 people and abducting 250 others. Weaponry based on Iranian designs, from mines to short-range rockets and drones, was widely used during the incursion and the ensuing fighting, Israeli officials have said.
The classroom notes, said to have been written by one of the trainees from Gaza, were shown to Bloomberg News by the intelligence officers, who did not disclose the details of when and how they were obtained.
An Israeli official with knowledge of intelligence affairs, speaking on condition of anonymity because of the sensitivity of the matter, could not comment on the provenance but said the weapons described corresponded with those wielded by Hamas and the allied militant group Palestinian Islamic Jihad. Both are designated as terrorist groups by the US.