No, it was obtained from the French by treaty, over 200 years ago, after the Brits whupped their asses in Egypt. Spoils of war.
But in any case, property, if held long enough, is owned by its possessor.
You know, an adverse possession claim would be very intriguing on an international scale... I'd love to read that opinion (and the jurisdictional disputes)!! Unbfortunately, to spoil my fun, it would probably be held up by Leftists and Globalists as a reason for instituting a world governing body.