Washington — A new United States Senate staff report recommends that Congress require Pakistan to cease all efforts to acquire a nuclear weapons capability as a condition for further American aid.
The 27-page report was submitted to the Senate Committee on Foreign Relations after a trip to Pakistan and India made earlier this year by Peter W. Galbraith, a member of the committee's minority staff.
As Mr. Galbraith points out, the Reagan administration's $3.2 billion security assistance program for Pakistan has been the subject of considerable debate in the Congress. When the program was first proposed three years ago, administration officials argued that the assistance would help to eliminate the feeling of insecurity that caused Pakistan to seek a nuclear-weapons capability. It is the third-largest American aid program, exceeded in size only by the military and economic assistance going to Israel and Egypt.
It is now widely believed here that despite this sizable aid program, which included the sale to the Pakistanis of sophisticated F-16 fighter planes, Pakistan continues to acquire clandestinely a nuclear weapons capability.
An improvement in US-Pakistan relations under the Reagan administration has been based on a common concern over the Soviet invasion of Afghanistan and agreement on the need for stability in the nearby oil-producing Gulf. But Mr. Galbraith argues in his report that the relationship remains ''exceedingly fragile'' and could be disrupted or dissolved by differences not only over nuclear policy but also over narcotics, human rights, the Arab-Israeli conflict, and India.
According to Galbraith, Pakistan sees India as its most serious security threat and stations more than two-thirds of its army on or near the Indian border. But, he says, many Pakistanis consider Afghanistan in the long run to be a potentially greater threat than India.
''The United States connection is valued because it provides Pakistan the superpower political support it feels it needs to balance the Soviet presence in Afghanistan,'' Galbraith writes.
Also on the positive side of the relationship, says Galbraith, are complementary efforts taken by the US and Pakistan to bolster the stability of oil-producing nations friendly to the West. Pakistan currently has at least two army battalions stationed in Saudi Arabia, pays a vital technical and advisory role in the Saudi armed forces, and provides much of the labor for Saudi military construction.
Galbraith says the US and Pakistan also share ''a common interest in enhancing moderate influence in the Islamic and Arab movements.'' As a leading force in the Islamic movement, Pakistan has been able to ''focus attention effectively'' on Afghanistan, according to Galbraith.
But Galbraith argues that in spite of the current honeymoon status of US-Pakistan relations, ''things could turn sour very easily.''
''Probably the single most important factor that could quickly and decisively destroy the relationship is Pakistan's nuclear program,'' he says.
By meeting Pakistan's security needs with modern conventional weapons, the Reagan administration argued that the incentive to go nuclear would no longer exist, Galbraith says. But he notes that current law effectively allows Pakistan to receive US assistance while pursuing a nuclear weapons capability, as long as it does not test a nuclear explosive device.
The staff report's author argues that US assistance has become increasingly important to the Pakistani government and that if more restrictive conditions were enacted, Pakistan would probably not act to jeopardize the six-year, $3.2 billion aid program, now at the halfway mark.
Since 1981, Pakistani officials have made public statements indicating that Pakistan is forgoing the nuclear option. But, says Galbraith, the US will have accomplished little if, at the end of the aid program, Pakistan has the facilities, material, and know-how to assemble quickly and detonate a nuclear weapon.
One way to stop this, Galbraith says, would be for the US to enact legislation requiring an aid cut-off unless Pakistan ceases efforts to acquire technology or material for nuclear weapons, or opens its facilities to inspection by the International Atomic Energy Agency.
California Sen. Alan Cranston (D) plans to introduce an amendment making aid contingent on a Presidential certification that Pakistan is not developing a nuclear explosive device and is not acquiring the necessary technology or equipment.
In his report, Galbraith recommends that the US fund the Pakistan aid package but use leverage gained thereby to promote nuclear nonproliferation, human rights, and narcotics control. He also argues that the US should not sell the AIM 9L Sidewinder missile for which, he says, security cannot be provided.
In a key recommendation, Galbraith says the US should support free elections. He says the elections announced by President Zia ul-Haq are widely seen as a means of legitimizing Mr. Zia's rule while excluding much of the opposition. Even a qualified US endorsement of these elections, he says, could damage US relations with a future democratically elected government.
Galbraith says the Pakistani decision on Jan. 10 of this year to release from detention Benazir Bhutto, the daughter of executed Prime Minister Zulfikar Ali Bhutto, came after nearly three years of effort on her behalf by Democratic Senator Claiborne Pell of Rhode Island and ''decisive intervention'' at the end of last year by Senator Charles Percy of Illinois, the chairman of the Senate Foreign Relations Committee.