Cuba is a sovereign nation, it can install missiles. Oh, wait..
Good example, US didn’t invade under DIRECT threat of nuclear missiles on Cuba’s soil.
Ukraine signed Budapest memorandum in 1994 and willingly gave up nukes for security assurances (ironically Russia is one of the guarantees).
There was no invasion because Soviets removed Cuban missiles and Kennedy promised to remove U.S. missiles from Turkey (the missiles being there is the reason for the crisis in the first place).
QED.
That definitely came out of nowhere and not because Russian soldiers occupied Crimea and effectively occupied east of Ukraine. Ukraine gave up nuclear weapons and Russia was one of the guarantors of Ukraine’s sovereignty.
And regardless of all of this, Ukraine is a sovereign nation and can do whatever the f””” it wants.