of weaponized mustard and nerve gas. Though not a belligerent in the Gulf War, Israeli cities were nevertheless bombarded by these upgraded Iraqi missiles. To compensate Israel for war-related damage and economic losses and keep German shipyards occupied with a high profile project in the post Cold War defense spending downturn, then Chancellor of Germany Helmut Kohl approved an assistance package to German industry including the construction of two Dolphin-class submarines. The names Dolphin and Leviathan hail from the retired Israeli WWII-era submarines of the British T class; the third boat Tekuma (translation: Revival) commemorates , the third Israeli boat of the T class which was lost in 1968 with all Israeli crew in the Mediterranean Sea during delivery. The names of the newer boats and are taken from retired s, which were themselves named after even older Israeli S-class submarines. Additional procurement In 2006 Israel signed a contract with ThyssenKrupp to purchase two additional submarines from its HDW subsidiary. The two new boats are an upgraded version displacing 28% heavier than the older Dolphins, featuring an air-independent propulsion system, similar to the one used on German Type 212 submarines. On 6 July 2006, the Government of Germany decided to finance an advance to start the construction, about €170 million, planned for delivery in 2012. The two submarines cost, overall, around €1.3 billion, of up to one-third was subsidized by Germany. In 2010, both Israel and Germany denied having talks regarding the potential purchase of a sixth submarine. Yet in 2011, Israel ordered a sixth Dolphin-class submarine, for which it was reported to pay the unsubsidized cost of US$1 billion. However, in July 2011, during a meeting between German Defense Minister Thomas de Maizière and Israeli Prime Minister Binyamin Netanyahu and Defense minister Ehud Barak, an agreement was reached to subsidize €135 million of the US$500–700 million cost of the sixth submarine. In 2016, it was revealed that a new sonar developed by Rafael Advanced Defense Systems had begun to be fitted on all Dolphin submarines in the last two years. The new capabilities provided to the Dolphin submarines by the Israeli sonar also include detection of vessels with a low noise signature. The algorithms used in the sonar systems enable it to ignore many of the noises that can disrupt the range of the systems' activity, while detecting very distant noises. In late 2016 reports emerged of negotiations for