While Japanese exports are saturating their markets with cheap steel, good cars and a dazzling range of electronic slaves, foreign countries don't have any doubt they're dealing with an economic superpower.

But Japan's economic strategists, more preoccupied with their nation's weakness than its strengths, have never quite accepted that image. Characteristically, in the midst of embarrassing export success, government and industrial planners see long-term difficulties in the two-way trade essential to Japan's survival. Their fears:

That world economic difficulties could lead to a cut-throat trade war with disastrous consequences for Japan's export-dependent economy Growing European and American criticism of Japan's booming trade surpluses last year has rewakened dormant fears of protectionism and boycott. Prime minister Takeo Fukuda has warned that a 1930s-style global trade slump could happen, with "very grave political consequences."

That the scarcity and increasing price of oil and raw materials gradually are undercutting Japan's competitive edge for the tough struggles ahead in the world industry has been killed by cheaper products from developing nations. High energy prices-effectively have ended domestic production of aluminium and now threaten the petrochemical industry with its $4 billion annual export trade. Other resource-reliant industries - paper, and even steel - will be vulnerable in the future.

That the long-heralded shift to sophisticated, knowledge and technology-intensive industries has met unexpected setbacks and delays. Experts argue that while such industries as autos and steel are peaking in world competitivity, Japan is lagging behind the U.S. and Europe in developing the next generation of products. They question whether Japan can catch up fast enough to export atomic energy, computers and aircraft.

Many foreign observers find that an unduly pessimistic set of apprehensions. They believe the dynamism of the Japanese managerial, industrial and sales force will allow them to triumph in the future as they have in the last 30 years of prodigious growth. Stil, granted a Japanese propensity for alarmist overreaction which usefully spurs the people to greater effort, the concerns are geniune and the questions they raise relevant.

"The real aftermath of the oil shock is still penetrating to the depths of our industry," said Eme Yamasita, formerly a vice minister in Ministry of International Trade and Industry (MITI). "We are losing ecompetitivess . . . and towards 1985 the long-run effects will be very serious." Japan now imports 300 million tons of oil a year at $1259 a barrel. If government plans achieve a stable growth in gross national product of 6 to 7 per cent annually. Japan will be importing 500 million tons of oil and paying up to $20 a barrel for it by 1985. Yamasita calculates. "We can hardly physically obtain that amount of oil," he added, "and it's doubtful we can export enough industrial goods to get the foreign exchange to pay for it."

MITI's director-general of basic industries, Naohiro Amaya, worries whether the world will stay peaceful and offer a forum for free trade: "A deterioration of world order to the 1930s situation of regionalism and protectionism would be disastrous for us," he said. "And I can smell the danger more now than in the 1950s and 1960s."

The oil crisis ended Japan's toyslike growth and fired her export drive with a national anxiety. Postwar industrialization accelerated during the Korean war (1950-53) with huge exports to American and left Japan with a structural reliance on export earnings to purchase food and essential raw materials. That dependence, and the consequent sense of insecurity, were greatly heightened when the imported oil which supplies 77 per cent of Japan's energy needs quadrupled in price. A 95-day stockpil and the average of six tankers a day which dock to replenish it are all that stand between Japan and what a MITI official flatly calls "mass panic."

Other nations are dependent on trade, but none see it as a challenge to survival as do the Japanese. Trade makes up 21 per cent of Britain's GNP, whereas in Japan it is generally only 10 per cent. Nevertheless, it is concentrated in a few key industries which prop up the entire economy. Japanese auto makers cranked out almost 8 million automobiles last year and exported about half - 1.37 million to the United States alone. The steel and consumer-electronics industries, which sell one-third of their products abraod, also are highly export-oriented. "If they lost half their exports in those three industries, it would have a massive multiplier effect on the whole economy - horrendous," theorized an American economist.

The Japanese have been attacked for running up a $10 billion world trading surplus last year, which critics say is a conspicuous case of over-eager exporting at a time when the world slowly is emerging from the worst and longest recession of the last 30 years. The nine European Community nations have bluntly said they will not tolerate another year like 1976 in which they ran an estimated $4.2 billion deficit with Japan. The U.S. also has sent word that it wants Japan's $5.36 billion surplus last year reduced and the flood of color televisions from japan - up 250 per cent from 1975 to 2.9 million of the 7.5 million sets sold in American in 1976 - is being investigated in two trade courts.

The chief television exporter to the U.S. is Toshiba, and the giant electronics manufacturer's export director, Shumnichi Murao, frankly conceded the company was looking for an export-led recovery. The Japanese domestic economy was kept on a short rein last year to curb inflation just within the government's 10 per cent target. "The domestic economy was very slow last year," explained Murao. "No factory wants idle capacity, so the emphasis went on exports."

Measures to restricts Japanese imports to the U.S. would penalize American consumers and Japanese manufacturers, Murao said. Then he repeated a question which is asked frequently and with much heat in Tokyo these days - why shouldn't Japanese manufacturers reap the reward of their automation and innovative modernization? At Toshiba's factory, two hours north of Tokyo 1,400 workers assemble 140,000 television receivers a month. In the last six years, the number of components have been cut by 40 per cent and the man-hours by 55 per cent, Murao claimed.

The superior efficiency and productivity of the Japanese factories is not disputed by the European Community's delegation head in Tokyo, Wolfgang Ernst. "It's a very unpleasant fact that we have become entirely undeveloped and uncompetitive in a number of manufactured goods - cars, steel, ships and some electronics," he said.

Ernst readily concedes the Japanese do not rely on low wages - pay scale have advanced almost 20 per cent a year in the 1970s - or unfair trade practices. "This is not dumping," he said. In what is plainly a modification of the free principle forced by political difficulties in Europe, the EC has asked for relief from certain Japanese exports and an increase of European exports to this country.

Japanese industrialis grumble about Europeans not working hard enough and then claiming special privileges. Unwilling to grant the smallest beachhead to the specter of protectionism, the government has been equally hard-headed. So far, there have been only promises and minimal concessions. The EC registered its disapproval last week by slapping a 20 per cent duty on Japanese ball-bearings.

Still, there is a dawning reality that while the EC nations - with the notable exception of West Germany - are struggling with deepseated economic ills, Japan must improve the trade balance or face the hated trade barriers.

The quandary for Tokyo's strategists is that the structure of their economy depends on earning an export surplus with the now-protesting EC and U.S. to pay the deficits they incur in importing energy and raw materials from other countries. Oil alone makes up 43 per cent of their export bill, costs a hulking $23 billion a year and leaves them $11 billion in deficit annually to the oil-producing countries. They also run an unavoidable $4 billion debt with Australia and Canada for the mineral ores they buy and turn into automobiles and other high-value-added products.

Japan's need to preserve export superiority over the exporting nations of the EC will lead to continuing rivalry and "20 years of difficulty," in one MITI official's gloomy prediction. More European goods probably will pierce Japan's web of subtle trade barriers and labyrinthine marketing system, but fundamentally the EC has no big-volume or high-price products which meet Japan's primary needs for raw materials and commodities. Because Japan and the EC also produce virtually identical portfolios of industrial products, the seeds of a long trade antagonism are visible in the current short-term squall.

The Japanese trade experts say they absolutely dependent on running a trade surplus with America. "If the U.S. rejects the imbalance, it would destroy Japan's economic ground and throw us into chaos," said MITI's Amaya.