The Importance of Reconquering Crimea

There's now thousands of mines on both sides of this increasingly sort of stable front. Every Ukrainian soldier I talked to, and that included several who had lost legs, two mines, talked about mines as a really major factor. Is it not illegal? Was there not a big treaty to stop putting down land mines there? And why is Ukraine, as well as Russia, ignoring it? Well, the United States didn't sign it either.