They were never a part of Argentina nor were there ever any Argentines on it before they decided to invade it in 1982. The islands were uninhabited before their discovery by the Europeans and long before there even was an Argentina
https://en.wikipedia.org/wiki/History_of_the_Falkland_Islands
Were the Hawaiian islands already occupied when you forcibly took them over ?
They also were never part of Britain. They were taken by Britain because of Britain's desire to create an empire and they were taken to enforce their military might.
And yep.. the Hawaiian islands were already occupied when we took them over.
Of course.. how about the American continent? Were their indigenous there before the British took them over? India.. Australia, New Zealand, Bahamas Barbados Jamaica Leeward Islands Antigua and Barbuda Dominica Saint Christopher (St Kitts)-Nevis
Windward Islands Grenada,Saint Lucia,Saint Vincent and the Grenadines,,ritish Guiana Berbice, Essequibo, Demerara,Falkland Islands,South Georgia South Sandwich Islands,Anglo-Egyptian Sudan (Sudan),Basutoland (Lesotho)
Balleland (Benin),Bechuanaland (Botswana),British East Africa (Kenya),British Somaliland (northern Somalia),British Togoland (eastern Ghana),British Cameroons (split between Nigeria and Cameroon),British Egypt Khedivate of Egypt
Sultanate of Egypt,Kingdom of Egypt,Gambia Colony and Protectorate,Gold Coast (Ghana),Colonial Nigeria Niger Coast Protectorate,Northern Nigeria Protectorate,Southern Nigeria Protectorate,Colony and Protectorate of Nigeria,
Northern Rhodesia (Zambia),Nyasaland (Malawi),Sierra Leone,South Africa British Cape Colony,Colony of Natal,Orange Free State,Transvaal Colony,South-West Africa (Namibia) Walvis Bay.Southern Rhodesia (Zimbabwe)
Swaziland,Tanganyika Territory (mainland Tanzania),Uganda Protectorate,Sultanate of Zanzibar (insular Tanzania), Burma, Ceylon (sri lanka), Samoan islands, Hong Kong, New Guinea, soloman islands, cypress, Malta..
And that's just what I can think of off the top of my head.
If you want to compare the US history of colonialism with the long, and illustrious bloody history of British conquest.. we can... but I don't think you will like the results.