Cyprus isnt. There are two sovereign base areas of Cyprus which are overseas U.K. territories, I guess similar to midway.
Islas Malvinas are Argentinian.
Not in these three fairly important ways: actual control, the wishes of the people who actually live there, de jure recognition by most countries. Otherwise, sure, totally and wholly Argentinian.
Yeah well... thats what england used to do, invade, put their own people to live there and then ask them if they feel like beloging to the crown.
You can ask Ireland.
I've got another one: historically
Argentina has tried to prove this both by legal means and by force, and has conclusively failed at both, so I think it's well past time to give up.