The recent testimony of a woman who said she saw a Philippine soldier shoot and kill former opposition leader Benigno Aquino has revived hopes in Washington for a fair trial of 25 military men and one civilian charged in connection with the assassination, according to State Department, congressional and Pentagon analysts.

Rebecca Quijano, testifying for 90 minutes last week in a Manila courtroom packed with about 400 persons, provided the prosecution with the first eyewitness account that contradicts the government's version of how Aquino was killed at Manila International Airport on Aug. 21, 1983.

Quijano's testimony and that of another witness last month have bolstered the prosecution's case at a time when its credibility had diminished. U.S. officials have underscored the importance of fair and impartial proceedings for the future of relations with Manila.

Since the trial began in February, the prosecution's case against the military had suffered from the disappearance of some key witnesses and refusal of others to testify. There were retractions as well.

Shortly after the trial began, President Ferdinand Marcos also announced that he would reinstate one of the defendants, his close associate Gen. Fabian Ver, as armed forces chief of staff if acquitted.

What happens to Ver is perceived by many in Manila and Washington to be the litmus test of credibility.

His reinstatement would bring a sharp reaction from Washington, which has been trying to promote reform in the Philippine military to combat a growing Communist insurgency. Washington has signaled Marcos clearly that it considers Ver a hindrance to implementing the needed reforms.

"It was a real coup on the part of the prosecution to get her to testify," said a State Department official of Quijano. Dubbed "the crying lady" after news film showed her weeping uncontrollably as she came off the same China Airlines plane that had carried Aquino back to the Philippines, Quijano dropped from sight shortly after the incident.

"She had a very good story. She was very poised and very clear," the State Department official said. "We think these are significant testimonies . . . . A month ago there were no witnesses."

"This is a critical moment now. If pressure is going to be applied to the court, it has got to be now," said a congressional analyst. "If there is any attempt to throw out the testimony or discredit it, it is going to look suspicious," he added.

When Quijano testified May 2, defense lawyers, in a surprise move, declined to cross-examine her. But these lawyers changed their minds this week and asked that she return to the stand, according to news agency reports from Manila. Defense attorneys have claimed that her testimony is not supported by physical evidence.

Yesterday, the three-judge panel hearing the case granted the defense's request and ordered Quijano to appear May 14, according to The Associated Press. The court also ordered immigration authorities to prevent her from leaving the country.

Lawyer Raul Gonzales has filed a motion for reconsideration, saying the defense had already waived its right to cross-examine her and that recalling her would endanger her life, AP reported.

Quijano, 32, a businesswoman, testified that she saw a soldier fire a gun into the back of Aquino's head. She also testified that Col. Vicente Tigas of Marcos' security command warned her not to testify about what she had seen.

The other witness, Ramon Layoso, a former security guard, testified that Aquino was still on a stairway leading down from the plane when the bullet that entered the back of his head was fired. His story contradicted the military claim that Aquino had reached the tarmac when an alleged Communist assassin, Rolando Galman, shot him. Galman was shot and killed moments after Aquino was killed.

Gen. Ver and 25 others are charged in connection with the slayings of Aquino and Galman. A fact-finding board appointed by Marcos ruled last year that the killing was plotted, carried out and covered up by military men. Ver and seven other defendants were charged as accessories in the cover-up, while 17 military men were charged as principals and one civilian as an accomplice.

So far, the evidence against Ver has been weak, and in the view of some Philippine and U.S. analysts, the testimony of Quijano will not make much of a difference in his case.

Many Filipinos have concluded already that Ver and Marcos were involved in the killing, said Walden Bello, codirector of the Philippine Human Rights Lobby, a coalition opposed to U.S. military aid to the Philippines. But for the international community, the testimony of Quijano is important because "the State Department has a lot of interest in the trappings of justice coming out of this trial. The trial is going to be one important factor in how they continue to relate to Marcos," he said.