In fact, ties between the Falklands and Argentina, which has claimed sovereignty over the islands since 1833, when Britain reestablished its rule of the archipelago, have not always been so tense.

Sheep farmers used to alternate between southern Patagonia and the Falklands. And well into the 20th century, some Falklands families would send their children to schools in Buenos Aires, like St. Andrew’s Scots School, that cater to Argentina’s large English-speaking community.

Mr. Peck said his first trips here in the 1990s tasted like “forbidden fruit.” He came to show his paintings, some of which deal with the war and its psychological scars. He met an Argentine woman and a romance ensued. They married and had two boys, who are now 9 and 5.

Living with his wife in Stanley, the capital of the Falkland Islands, proved difficult, Mr. Peck said, partly because of hostility toward her. And with Argentina still limiting flights to the Falklands in its airspace, having to fly home via Chile did not help, he said.

When his wife returned to Argentina with their sons, Mr. Peck followed, though they have since separated. He said his decision to obtain Argentine nationality was largely about being able to live closer to his sons.

BRANDED a traitor by some in the Falklands, including people he grew up with, Mr. Peck described death threats he received by e-mail. The threats prompted Argentina’s foreign minister, Héctor Timerman, to contend at the United Nations that Britain would be to blame if Mr. Peck suffered harm from “fanatics” on the islands. “In the world of black-and-white thinking, it’s a defection,” he said. “But in my mind it’s not.”

Months later, tempers still flare over Mr. Peck’s decision, even if some reactions are more restrained.