From the beginning of time imperial powers have been embarrassed by their small clients, particularly when their small client states are ruled by dictators with ambitions of their own and with slight regard for human or civil rights.
This week it was the United States that once again was embarrassed by the behavior of one of its most important clients, this time President Ferdinand Marcos of the Philippines.
A particularly spectacular assassination took place in his airport at the foot of the ramp down which had come his most prominent rival for the presidency of the Philippines, Benigno Aquino. President Marcos promptly denied that he had in any way arranged or connived at the assassination. But, in view of the known facts, his denial failed to convince his critics.
Government security police controlled the area around the aircraft. Three of them went with Mr. Aquino down the ramp. The bullet was fired from behind at a distance of two or three inches, according to a coroner. An alleged killer was gunned down immediately after Mr. Aquino.
The trajectory of the bullet was downward, according to the official autopsy. The alleged killer was shorter than Mr. Aquino. The course of the bullet would more logically indicate that it had been fired from behind by someone still on the ramp than by a shorter person at ground level. The only person known to be above and behind Mr. Aquino at the crucial moment was one of the three security guards.
Besides, with the whole airport and field under tight security control, how could anyone have been able to get so close to Mr. Aquino without the consent or connivance of the security guards?
President Marcos is important to the United States. He negotiates at regular intervals with Washington for renewal of the US lease on the big US naval base at Subic Bay and the equally important US air base at Clark Field.
Those two bases are the main forward bases for US military power in the far Pacific. They were less important back when the US had still more forward bases in Vietnam.
But today the Soviets enjoy the bountiful anchorage at Cam Ranh Bay with all the piers and wharfs which Washington built at vast US expense; also the various airfields that once serviced US air forces in the Far East.
More than ever today Subic Bay and Clark Field are important to the US Navy and the US Air Force. The biggest Navy ships can be repaired at Subic Bay. Were it not available, those ships would have to go back halfway across the Pacific to Pearl Harbor or all the way back to the Pacific Coast. They can go to Japan for ''rest and recreation.'' But their forward bases are in the Philippines.
President Marcos is a hard bargainer.
His wife, Imelda, has a habit of going off on a visit to Moscow when terms of the lease are coming up for reconsideration. She is a frequent world traveler. She called on Libya's strong man, Muammar al Qaddafi, in his capital, Tripoli, in 1976, again in 1977. She likes to visit both Moscow and Peking. President Marcos has more than once hinted, broadly, that if he doesn't get enough rent from the US for the bases, he might turn to someone else.
His record in the human and civil rights departments is at best flawed. His prisons contain many political prisoners. The treatment of them has been the subject of frequent criticism by civil rights watchers. The world gasped with astonishment and disbelief in 1981 when US Vice-President George Bush told Mr. Marcos that ''we love your adherence to democratic principles and to the democratic processes.''
The price for the bases comes high, indeed, when it has to include such official hypocrisy. It may be raised still higher if President Reagan follows through on his planned visit to the Philippines in November -- despite the Aquino assassination. At least when South Korean President Chun Doo Hwan visited the White House just after the Reagan inauguration, the administration got a tacit quid pro quo: the commuting of the death sentence on Chun's leading civilian opponent, Kim Dae Jung.
Difficulties with dictatorial and unruly clients is nothing new in history. Perhaps the best known example is that of King Herod. His extravagance and his brutality (the ''slaughter of the innocents'') finally proved too much for the Romans. They eventually suppressed the Jewish monarchy.
The Soviets have their troubles with clients and puppets too. Babrak Karmal tries to run Afghanistan for them. His trouble is largely incompetence. He simply has not been able to generate enough local support to be a plausible local client.
The US, partly because of its tendency in these times to change governments every four years, has an uneven record. It seems never to be able to decide whether to press for respectability on the part of clients, and make that a test for US aid, or back them regardless of their local behavior toward their own people.
During the Carter years the emphasis was on pushing them to clean up their acts. Aid was withheld from those whose human rights record was unseemly. The new Reagan administration discarded all that and measured clients by their alleged anticommunism. Argentina, Chile, South Africa, South Korea, and the military dictatorships of Central America were promptly admitted back into a state of grace in the eyes of Washington.
The American record on supporting undemocratic clients has produced one particularly spectacular failure since World War II. The Shah of Iran was for long the fair-haired boy of Washington. He was enthroned by Washington, aided lavishly, encouraged to buy one of the world's best stocked arsenals, and treated ''royally.''
But then he lost his Peacock throne. His arsenal fell into the hands of a passionately anti-American religious fanatic. The subsequent story of the hostages was an important reason for the downfall of the Carter administration.
The Soviets seem to have learned from experience to be careful in their support of clients. They are less generous in aid, keep clients on a shorter rein. They had their own disaster with Egypt. They provided it generously with weapons right through the 1973 war. Then Egyptian President Anwar Sadat decided to switch sides and turn to the US for economic aid and military support.
The Soviets have not since been as generous with their clients. Their weapons in Syria during the recent Israeli invasion of Lebanon were obviously of Class B quality. The Soviets have only this year replaced them with better and later Soviet models, but then they sent their own people along to use, and protect, those better weapons.
The Soviets have not risked losing as many weapons as the US lost in China in 1949 and later in Vietnam. They prefer to keep their clients under either tight control (when possible as in Eastern Europe) or on short rations elsewhere.