A red star above a hammer and sickle is fast becoming emblazoned across the Ethiopian political landscape. The communist insignia can be seen painted on the windows of the capital's international airport, posted on government office walls and now imprinted on the flag of the country's embryonic Soviet-style party.

Western embassies sift with a fine-tooth comb through the latest speech of "Comrade Chairman" Mengistu Haile-Mariam, the country's military strongman, for signs of his true colors, hoping to find the fires of nationalism still burning more brightly than those of his openly professed communism.

Ethopian officials, meanwhile, assert there is no conflict between their intense sense of nationalism, anchored in this country's 2,000-year-old history as an independent empire, and their new-found faith in "proletarian internationalism," rooted in a violent revolution that shattered the old order in 1974 and outside communist promises of aid to help in building a new socialist one.

"We are both dedicated nationalists and dedicated communists," remarked one government minister.

"I have been reading through the writings of Lenin and I find he was a nationalist first," said another high-ranking official. "So why can't we be both nationalist and communist, too?"

Of all the Soviet Union's Third World allies, none is a more fascinating study of the often conflicting mix of these two powerful forces -- nationalism and communism -- than Ethiopia. This is particularly true today as Marxist Ethiopia puts to the test the economic strengths and weaknesses of its newly found communist allies and weighs the potential value of an even closer economic association with them.

In more than one sense, the relevance of communist ideology and theory of development is being put to the test on the harsh terrain of one of the world's least developed economies.

Increasingly enmeshed in alliances with Soviet Bloc nations, imitative of their foreign policies, Ethopia would seem to have all the makings of an African-style Cuba. It is even seeking associate membership with COMECON, the East Bloc common market.

"They are creating the institutions that are communist even if there are still very few dedicated communists," remarked one Western diplomat somewhat skeptical of Ethiopia's professed intentions to become a communist state. "The hold of Ethiopian culture and tradition is far stronger than anything I have experienced in any other country."

One centuries-old Ethiopian tradition is exploiting to the fullest extent a foreign power to preserve national independence and extract the maximum in assistance for its own ends.

Ever since a 16th-century Christian Ethiopian emperor, Lebna Dengel, made use of 400 Portuguese musketeers to defeat the invading Moslem army of Ahmed Gran, the man Somalis recognize today as their first great nationalist leader, Ethiopia's rulers have allied themselves to one European nation after another to bolster their own forces and defeat the enemy of the day.

But no outside power has remained an ally for very long and attempts to impose control or unwanted influence have been fiercely resisted. The most recent discarded ally was the United States, which gave $350 million in economic asistance and $280 million in arms before Ethiopia broke with it in April 1977 and turned to the Soviet Union to fill the gap.

It is precisely this Ethiopian tradition that is making it difficult for outsiders, including the Soviets, to assess the true direction of a violent social revolution that has taken this country in six years from a feudal empire to a radical socialist state and from being a faithful ally of the United States to just as close a friend of the Soviet Union.

The outcome could well hang less on what the Ethiopians do than the Soviets. For Moscow is facing mounting demands from the Ethiopians for more assistance, an issue that is creating an underlying malaise in their outwardly close relations that may one day drive the two apart.

"Economic problems are likely to affect relations with our friends," commented Negussay Ayele, chairman of the political science department at Addis Ababa University.

"The Soviets have proven to be friends to our aid at a time of great crisis. It give up a warm relationship with Somalia to stand behind our revolution," he said, referring to the Soviet expulsion from Somalia in 1977 after Moscow began sending arms to Ethiopia as it was being invaded by Somalia forces.

"The question is, can they continue it in peacetime? Can the socialist world give the kind of assistance in quantity and quality that would have a difference on the course of our revolution?"

The question is of more than passing academic interest.

With American, West German, British, Canadian and World Bank aid either tapering off or frozen mainly because of Ethiopia's refusal to compensate Western owners of nationalized properties, the Mengistu government has had to look primarily to the East.

Increasingly burdened by the economic or political problems among its East Bloc allies and within its own borders, however, the Soviet Union appears unable, or unwilling, to provide the vast amounts of economic aid Ethiopia is becoming desperate to obtain to consolidate its revolution or even remain afloat.

Ethiopian economists calculate they will need $21 billion in investments during the coming decade just to double the present $131 per capita income of the country. It is presently receiving the least amount of capital inflow for its size of any African country, only $130 million last year, ironically most still from the West with the World Bank, the European Common Market and Sweden in the lead.

"The flow has not been encouraging either from the East or the West," remarked an official of the government's Central Planning Supreme Council. "We simply are not receiving enough foreign aid and grants."

Ethiopia watchers see the problem writ largely in the latest Soviet-Ethiopian joint communique issued Nov. 10 at the end of Mengistu's two-week state visit in the Soviet Union. The local press reported at the conclusion of two days of talks between Mengistu and Soviet President Leonid Brezhnev that "great attention was devoted to examining questions of Ethiopian-Soviet economic cooperation."

Yet the final lengthy communique hailing the two government's total identity of views on foreign policy issues and ever expanding relations in all fields contained just one paragraph concerning Soviet economic assistance. Significantly, this referred to the signing of protocols for aid projects already agreed upon as far back as 1978.

"The communique was more significant for what it didn't say than what it said," remarked a Western diplomat after a careful reading.

The most immediate problem facing Ethiopia -- about which nothing was said in the joint Soviet-Ethiopian statement -- is getting low-cost oil

Last year, this country spent 36 percent of its total export earnings, mostly from coffee, on oil imports. In the 1980-81 fiscal year, it will devote to oil more than 50 percent of its roughly $500 million in anticipated export revenues, according to the estimates of the government's Central Planning Supreme Council.

"It's becoming intolerable," said a council spokesman, pointing out that in 1974 at the beginning of the revolution Ethiopia had spent only $15 million on oil imports. "Some economic projects have had to be scrapped and some postponed because of this.

Late last year, Mengistu sent his economics czar, Addis Tedla, to Moscow to plead for help. But Tedla got only an nine-month commitment to provide Ethiopia with crude oil for its Assab refinery at the very reduced price of $19 a barrel.

A renewal of this contract is believed to have been a primary objective of Mengistu's fall visit to Moscow and his talks with Kremlin leaders. Western sources here believe they agreed at best only to another short term contract and this explains Mengistu's unexpected stop in Tripoli on the way back from Moscow for talks with the Libyan leader, Muammar Qaddafi.

Ethiopia's problems with the East Bloc to not stop with oil, however. They include other forms of expected communist economic aid that has been slow to materialize. These are primarily credits and loans rather than outright grants such as Ethiopia was getting from its former Western partners and still obtains from Scandinavian countries, such as Sweden, by virtue of its being on the world's least developed nations.

The difficulty of economic relations between the Soviet Bloc and its Third World allies is summed up in Moscow's aid program here. On paper, Moscow has extended 180 million rubles ($200 million) in economic credits to Ethiopia. But half this amount was given back in 1959, when the late emperor, Haile Selassie, ruled this land, and still only 20 million of the total has been spent.

The Soviets are discussing a wide variety of projects, including a cement factory, an irrigation scheme, expansion of the Assab refinery they originally built in the 1960s, a tractor assembly plant, modernization of a gold mine and drilling for oil and gas in the Ogaden in place of an American firm.

But none of them, aside from the gold mine, has gotten off the ground yet for various reasons, although Moscow did give $4 million to $5 million in outright grant aid this year, including 12,000 tons of wheat, and is providing upwards of 3,000 scholarships for Ethiopian students.

As the limits of East Bloc aid become more apparent, there are straws in the wind of Ethiopian movement on the sticky compensation issue involving around $200 million in claims. Even a beginning of a resolution would probably be sufficient to get new loans from the World Bank, the biggest single provider of aid to this country even today with $120 million still in the pipeline.

In the past few weeks, a number of foreign companies with outstanding claims, including two American ones, have been invited by the Ethiopian government to send representatives for discussions. While it is still too early to speak of a breakthrough, this is the first sign of a reevaluation by Ethiopia of its need for Western assistance that could eventually affect its long-term relations with the Soviet Bloc.