Air and Air Defence Forces Army – Rostov-on-Don) 37th Composite Aviation Regiment (Simferopol) (Two Squadrons: Su-24 and Su-25) 38th Guards Fighter Aviation Regiment (Sevastopol) (Two Squadrons: Su-27/Su-30SM the latter with Oniks (Yakhont) supersonic anti-ship missiles) (may partly re-equip with Su-57?) 39th Helicopter Regiment (Dzhankoi) has been equipped with Mi-35M attack helicopters, Ka-52, Mi-28N, and Mi-8AMTSh helicopters (as of 2016). 31st Air Defense Division (HQ: Sevastopol) subordinate to the 4th Air and Air Defense Forces Army (HQ: Rostov-on-Don) 12th Anti-Aircraft Missile Regiment 18th Anti-Aircraft Missile Regiment Five battalions with S-400 SAM systems (250–400 km range) S-300 long-range surface-to-air missiles with Nebo-M radars. Four battalions: Pantsir-S medium-range SAM Buk SAM system 51st Air Defense Division (HQ: Rostov-on-Don; with S-400, S-300, Pantsir, Buk SAM systems subordinate to 4th Air Army) 1537th Anti-Aircraft Missile Regiment (Novorossiysk, Krasnodar) 1721st Anti-Aircraft Missile Regiment (Sochi; may have started re-equipping with S-350 surface-to-air missile systems in May 2021). 1536th Anti-Aircraft Missile Regiment (Rostov-on-Don) 7th Military Base (Primorskoe, Abkhazia – S-400 and S-300 SAMs) Incidents The Russian Black Sea Fleet's (BSF) use of leased facilities in Sevastopol and the Crimea was sometimes controversial. A number of incidents took place: For security reasons, the BSF refused to allow Ukrainians to inspect its aircraft cargo, after allegations by Ukrainians that they could be carrying nuclear weapons, which would have infringed upon Ukraine's status under the Nuclear Non-Proliferation Treaty (NPT) The BSF transported rockets repeatedly through the port of Sevastopol without seeking permission from Ukrainian authorities. A lighthouse is located on the headland which, starting in 2005, was the subject of a controversy between Ukraine and Russia. From August 3, 2005, the lighthouse was occupied by the Russian military. Despite a controversial ruling by a Court in Sevastopol on the subject, Russian military officials referred to the fact that they only took orders from the chief of the Russian Navy headquarters and no one else. Ukrainian activists complained that Sarych was illegally occupied by the Russian Navy. As a military facility, the territory around the Sarych headland is closed to trespassers with barbed wire, and the Russian flag flew over Sarych. In 2006, Ukrainian officials blocked Russian workers from entering the BSF lighthouse in Yalta. During the 2008 South Ossetia War, the Ukrainian Navy was ordered to block the entrance to Sevastopol from Russian vessels taking part in the hostilities. However, Russian Navy ships returned to base unimpeded by the sympathetic Ukrainian