Islamic Jihad released pictures on Thursday of the new rocket with a heavy warhead, which they announced had been fired toward Ashkelon during the escalation of violence earlier this week.The IDF has been concerned about heavy mortars which could carry 150-200 kilogram warheads, and which would inflict heavy damage on the Israeli home front. On Thursday, the group released images showing at least 12 small, locally produced improvised rockets made from a large metal canister. Due to its oversize warhead, the small, local rocket has greater destructive capabilities – although, compared to other rockets in Islamic Jihad’s arsenal, it has less accuracy and range.According to Tal Inbar, an expert in rocketry at the Fisher Institute for Air and Space Strategic Studies think tank, it is the first use of such a rocket by a terror group in the Gaza Strip against Israel.“The amount of explosives is several times heavier than in standard rockets which have the same diameter, such as the Grads,” he told The Jerusalem Post on Thursday, adding that while “range is affected it causes more damage.”While one image released by Islamic Jihad showed the rocket fired from its stand during the day, both Hamas and Islamic Jihad have carried out tests on their rocket arsenal on an almost regular basis since the conclusion of Operation Protective Edge, firing rockets toward the sea in an attempt to increase their range and destructive power.“We have heard for months that they [Hamas and Islamic Jihad] are conducting rocket tests... this was the first opportunity to use it,” Inbar said of the new missile.With Hamas working on improving ties with Egypt, weapons smuggling into the blockaded enclave from the Sinai Peninsula has decreased, leading terror groups to invest in producing their own locally-made rockets.“You cannot block email and phone-calls needed to get the knowledge to build such a rocket,” Inbar said, adding that “it is not rocket science” to build such rockets and “the technical infrastructure to produce them is relatively low-tech.”Last March, Army Radio reported that Hamas had developed a new high-powered short-range rocket which has a range of 10 kilometers. According to the report, the group has produced several dozen of the rockets which carry a relatively heavy explosive load, from dozens to hundreds of kilograms each – similar to Hezbollah’s short-range Borkan rocket, which weighs between 100-500 kilograms.The IDF has warned that terror groups in the Strip have restored their military capabilities to their pre-2014 strength, expecting that in the next war the southern communities bordering the Gaza Strip would be incessantly pounded with rockets and mortar attacks.The recent explosion of violence in the South saw close to 500 rockets and mortars fired on southern Israeli communities, killing one man and injuring close to 100 other civilians, two seriously. One soldier was critically injured by an anti-tank missile fired at a bus.According to Inbar, it is likely that the rocket which struck the residential building in Ashkelon Monday night was the heavy rocket launched by Islamic Jihad.“The damage was quite dramatic as compared to the destruction caused by other rockets, so a heavy warhead was the most probable cause,” he said, stressing nonetheless that it could only be confirmed with an examination of the rocket fragments by authorities.