level – the Arrow system, jointly funded and produced by Israel and the United States. The Iron Dome system against short-range rockets is operational and proved to be successful, intercepting hundreds of Qassam, 122 mm Grad and Fajr-5 artillery rockets fire by Palestinian militants from the Gaza Strip. David's Sling, an anti-missile system designed to counter medium range rockets, became operational in 2017. Israel has also worked with the US on development of a tactical high energy laser system against medium range rockets (called Nautilus or THEL). Israel has the independent capability of launching reconnaissance satellites into orbit, a capability shared with Russia, the United States, the United Kingdom, France, South Korea, Italy, Germany, the People's Republic of China, India, Japan, Brazil and Ukraine. Israeli security industries developed both the satellites (Ofeq) and the launchers (Shavit). Israel is known to have developed nuclear weapons. Israel does not officially acknowledge its nuclear weapons program. It is thought Israel possesses between one hundred and four hundred nuclear warheads. It is believed that Jericho intercontinental ballistic missiles are capable of delivering nuclear warheads with a superior degree of accuracy and a range of 11,500 km. Israeli F-15I and F-16 fighter-bomber aircraft also have been cited as possible nuclear delivery systems (these aircraft types are nuclear capable in the US Air Force). The U.S. Air Force F-15E has tactical nuclear weapon (B61 and B83 bombs) capability. It has been asserted that Dolphin-class submarines have been adapted to carry Popeye Turbo Submarine-launched cruise missiles with nuclear warheads, so as to give Israel a second strike capacity. From 2006 Israel deployed the Wolf Armoured Vehicle APC for use in urban warfare and to protect VIPs. Commemoration Commemoration Yom Hazikaron, Israel's day of remembrance for fallen soldiers, is observed on the 4th day of the month of Iyar of the Hebrew calendar, the day before the celebration of Independence Day. Memorial services are held in the presence of Israel's top military personnel. A two-minute siren is heard at 11:00, which marks the opening of the official military memorial ceremonies and private remembrance gatherings at each cemetery where soldiers are buried. Many Israelis visit the graves of family members and friends who were killed in action. On the evening before the remembrance day all shops, restaurants and entertainment places must close gates to the public no later than 7 P.M. (the same routine and law applies to the