Ukraine has acceded to the Nuclear Non-Proliferation Treaty. Ukraine inherited approximately 5,000 nuclear weapons when it became independent from the Soviet Union in 1991, making its nuclear arsenal the third-largest in the world.[111] By 1996, Ukraine had agreed to dispose of all nuclear weapons within its territory, with the condition that its borders were respected, as part of the Budapest Memorandum on Security Assurances. The warheads were disassembled in Russia.[112] Despite Russia's subsequent and internationally disputed annexation of Crimea in 2014, Ukraine reaffirmed its 1994 decision to accede to the Nuclear Non-Proliferation Treaty as a non-nuclear-weapon state.
Judge for yourself if Ukraine's border is being respected by Russia.
Ukraine must be having buyer's remorse on that deal. But regardless, I guess the heat from Russia would be too much for Ukraine, if they had either kept their nukes, or at this point started their own nuclear program.
