Washington — Whether or not the Falklands crisis comes to a shooting war, a British-Argentine war of a different kind already is being fought out in board rooms and banks around the world.
The weapons of this war are economic. They involve trade, credit, loans -- and huge sums in dollars and pounds sterling.
In the long run, some experts say, Argentina could be humbled more effectively by economic warfare than by any shells or missiles flashing from British warships.
But the weapon is two-edged. For Prime Minister Margaret Thatcher's domestic economic recovery program also could be undermined by the unexpected costs of waging war.
Maintaining a large fleet 8,000 miles from home will balloon military spending. If the operation is prolonged, it could well force Mrs. Thatcher to raise taxes or cut spending elsewhere.
Separately, the pound has been dropping in value since the crisis began. This trend adds to the cost of imports and boosts domestic inflation.
Other powers -- including the United States and the Soviet Union -- have more than a passing interest in what goes on, too. Both superpowers have substantial economic stakes in Argentina.
This provides some added incentive to Washington to try to end the dispute. President Reagan announced April 14 that Secretary of State Alexander M. Haig Jr. would resume his shuttle diplomacy with another trip to Buenos Aires in quest of a formula to preserve peace.
''The situation is most sensitive,'' said Mr. Reagan in the White House Rose Garden. ''Nonetheless, ideas have been presented which are being seriously considered on both sides.''
The Soviet Union now buys about 75 percent of all grain exported by Argentina , according to Prof. Riordan Roett, director of Latin American studies at the School of Advanced International Studies of Johns Hopkins University.
Because the Soviet grain harvest is well short of consumption goals, grain shipments from Argentina -- Moscow's largest trading partner in Latin America -- are extremely important to the Kremlin. Moscow's trade deficit with Argentina runs more than $3 billion a year, largely because of Soviet dependence on Argentine grain.
The United States, for its part, has economic interests of a different kind in Argentina, including $2.5 billion worth of direct investment by American companies, according to US government figures. American chemical firms ($415 million) and oil companies ($400 million) top the list of US enterprises owning manufacturing and other facilities in Argentina.
Apart from this, cash-short Argentina owes US banks $9.2 billion, according to the Federal Reserve Board -- well over one-fourth of Argentina's total foreign debt of $32 billion.
Much of this foreign debt is short-term, with more than $16 billion coming due in 1982. To pay its debts, Buenos Aires needs two things: unhampered foreign trade through which to earn hard currency, and access to Western credit markets.
What Britain so far has done is to freeze Argentine assets in Britain, including bank deposits, forbid British banks to loan more money to Argentina, and halt merchandise trade.
Britain's nine Common Market partners supported London by banning all imports from Argentina. Australia and Canada have followed suit, and Britain hopes other Commonwealth nations will do the same.
All this shuts off more than one-quarter of Argentina's normal export market, meaning that its earnings from trade will shrink so long as the embargo lasts.
The Common Market, however, left it up to individual member countries to decide whether or not to extend new financial credits to the regime of President Leopoldo F. Galtieri.
To prevent any British creditor from declaring Argentina in default, Buenos Aires has set up an escrow account in New York, into which payments due British or British-based creditors will be made. This is part of a widely supported Argentine strategy to avoid default, which would jar the international banking system and cause the seizure of Argentine assets around the world.
US, European, and other bankers hope to be able to muddle through, collecting at least minimal Argentine debt payments, until the Falklands crisis is over.
The preference of international bankers -- relative to Argentina and other debt-burdened countries like Poland -- is to accept even small payments on outstanding debt rather than risk the loss of the whole loan through default. Few if any banks, however, are expected to lend fresh funds to Argentina until the potential of war over the Falkland Islands subsides.