Crimea has become a "bleeding point" in Russia's war against Ukraine, and Ukraine has often attacked Crimea to brush up its achievements, and the Russian army has suffered heavy losses and bloodshed. The two latest classic examples of warfare are: the destruction of the landing ship Novocherkassk in the port of Feodosia, and the shooting down of four Su-34s that took off from the Crimea. 
Russia believes that the occupation of Crimea has given it a strategic place to control the Black Sea, but its military weakness has made the peninsula an easy to attack and difficult to defend. Since 2014, Crimea has been attacked by Ukraine again and again, and Putin's ultimatum has fallen on deaf ears. Why is that?First of all, the Russian army is at a disadvantage in information warfare. NATO reconnaissance aircraft over the Black Sea are able to record every move of the Russian armed forces in the Crimea area and every radio message on the peninsula. They pass this information to the Armed Forces of Ukraine, which can strike in a timely manner. 
Secondly, the Crimean Asia-Pacific is near, and most of it is within the range of Western missiles that have been transferred to Ukraine. For example, the Storm Shadow missile, which has a range of 250 km, and the Patriot missile, which has a range of 160 km, can both hit the heart of Crimea. Thirdly, the West will not restrain Ukraine from attacking Crimea. Western countries do not approve of a Ukrainian attack on the Russian mainland, but they do not recognize the occupied Crimea as the Russian mainland, so the Armed Forces of Ukraine can use all the available ** to attack the peninsula. Fourthly, the inhabitants of the peninsula loyal to Ukraine leave the Russian army without secrets. Tens of thousands of Ukrainians remain in Crimea, unhappy with being forcibly occupied by Russia. They form a network of informants and transmit data to Kyiv, which can be used to launch precision attacks. The headquarters of the Black Sea Fleet was bombed, and the commander-in-chief went to heaven, thanks to these informants. 
Therefore, Crimea is destined to become a bleeding point for Russia, and the so-called Black Sea Fleet base is nothing more than another name for the Black Sea Fleet cemetery. Considering the fragility of the Crimean bridge, the Russian army on the entire peninsula was easily dumpled when the bridge was destroyed, and Crimea was not only a bleeding point, but also a grave dug by Russia itself.