Both military and diplomatic strategies have accelerated over the Falkland Islands dispute. The British government stands firm amid fervent hopes here that war with Argentina can be averted.
On the diplomatic front, United States Secretary of State Alexander Haig's mediation mission to both sides, now under way, is welcomed by London, with Prime Minister Margaret Thatcher insisting that he came to London as a friend and ally rather than an honest broker.
The military strategy behind Britain's diplomacy tightened a notch with the announcement that Britain will enforce a 200-mile radius interdiction zone around the Falklands beginning Monday. British Defense Secretary John Nott warned that any Argentine ship coming within 200 miles of the islands risked being sunk. ''We are earnest and no one should doubt our resolve.''
The move, a virtual blockade, is designed to force the Argentine junta to think again and to yield the administration of the islands back to Britain.
It is also aimed at impressing Argentine public opinion and prodding it into protesting the junta's occupation.
To go along with the military stick, Britain holds out a carrot: ''Take off your men, and we will take part in talks to achieve a lasting solution to the islands' future.'' But Mrs. Thatcher refuses to begin talks before occupation forces leave, and she is reported to have insisted on that to Mr. Haig.
The secretary of state was due to fly to Argentina April 9.
Britain may eventually have to accept a diplomatic solution. One being suggested by several national newspapers and opposition politicians is known as a ''Hong Kong arrangement.'' This would see Argentina take sovereignty and immediately lease back the islands to Britain for a lengthy period.
The islanders themselves have rejected this plan in the past. Many said they would rather leave than live under Argentine rule.
This could change if they are assured that British democracy, way of life, supplies, and markets for Falkland wool will remain.
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