At the end of November Ukraine attacked two Russian airbases for heavy bombers. These bases were deep inside Russia and Ukraine attacked them using an old six-ton Tu-141 Soviet surveillance UAV. The Tu-141 flew slow (below the speed of sound) and low to take pictures or radar images of what was below. Its INS (inertial navigation system) was less accurate than GPS, which wasn’t available in the 1980s. INS kept it on course for distances of up to a thousand kilometers, at which point the Tu-141 turned around and returned to its base where it landed by parachute. Some repairs were needed after each flight. The similar but smaller (1.2 ton) Tu-143 had a smaller payload and a range of only 200 kilometers. Over 900 Tu-143s were produced in the 1980s and Ukraine inherited many of them, plus most of the Tu-141s, when the Soviet Union collapsed in 1991. Some countries, like Russia, North Korea and Syria, still use the Tu-143. Tupolev, the Russian manufacturer of these UAVs is still working on a Tu-300 with a modern navigation system and the ability to carry weapons or additional sensors.
Ukraine stored its Tu-141s and 143s after 1991 and recently took some out of storage, refurbished them and installed some new features which were not made public. Ukraine secretly conducted some test flights but one of these tests ran into problems and in March two of the test models crashed, one in Ukraine and the other, two days later in Croatia. This one flew undetected over Romania and Hungary before crashing in Croatia, where it caused no damage. Ukraine denied that it belonged to them but Russia insisted it no longer used its Tu-141s.
Ukraine kept working on the Tu-141s and 143s and is believed to have installed a new guidance system using modern INS and GPS. This enabled the UAVs to act as cruise missiles when equipped with explosives and sent on one-way missions.
Russia protested these attacks on its air bases deep inside Russia. Ukraine pointed out that these bases were used by heavy bombers that regularly carried out attacks on Ukraine using air-to-surface missiles. The United States, the largest provider of weapons to Ukraine, agreed that those were legitimate military targets since so many Russian missile attacks are launched from Russia, especially attacks on civilians. The Ukrainians are justified in retaliating any way they can. This policy change may mean the Americans will send Ukraine longer range missiles. In the meantime, the Ukrainians will improvise, and they have a lot of Tu-141s and 143s to work with. This means the vital Kerch Strait bridge is in danger of suffering more damage. The railroad portion of the bridge is still being repaired and there is only very limited traffic on the surviving road bridge. Another few missile hits on the bridge and its rail and both road portions will be out of action for the rest of the war. That means supplying Crimea becomes very difficult and Russia will have a more difficult time stopping the continuing Ukrainian offensive in the 18 percent of Ukraine they still occupy.