Congress threatens to end Pakistan aid over nuclear program. But US also wants to keep Pakistan's support of Afghan guerrillas

United States relations with Pakistan are running into a congressional firestorm. American lawmakers are irate at Pakistan's latest apparent attempts to obtain US-made material for its nuclear weapons program. They are threatening to cut off all US aid to the strategic South Asian nation.

This, in turn, could undermine the flow of assistance to the Afghan resistance fighters based in Pakistan.

A senior US official is expected in Pakistan this weekend for talks with President Mohammed Zia ul-Haq. Michael Armacost, undersecretary of state for political affairs, will try to sort out a dilemma:

How to balance Pakistan's vital role on Afghanistan's border against strong evidence that it is developing nuclear weapons - and violating US law in the process.

Pakistan is a major recipient of American aid. The Reagan administration, which has welcomed Pakistan's support for the Afghan guerrillas, is proposing a $4.02 billion assistance package over the next six years.

All US aid could well be cut off Sept. 30, however, according to congressional sources - unless Mr. Armacost brings back some convincing explanations about the illegal export cases, and Congress sees tangible evidence of new safeguards on Pakistan's nuclear program.

US officials warn that a cutoff could endanger the flow of aid to Afghan resistance fighters and the 3 million Afghan refugees in Pakistan. Without US aid and support, they say, Pakistan would also be tempted to placate Moscow, which has 115,000 troops in Afghanistan. Ironically, officials add, Pakistan could also be pushed to move forward rapidly with its nuclear program in a search for security.

These sources see the diplomatic task as finding a formula that rebuilds Pakistan's nuclear credibility in Washington while preserving ``a broadly supportive relationship.''

US officials would like to see Pakistan accept safeguards at its Kahuta nuclear enrichment facilities, where weapons-grade uranium has reportedly been produced. But there is strong popular support in Pakistan for a nuclear weapons option, and the officials say President Zia cannot be seen at home to yield too much on the program.

American aid to Pakistan was halted in 1979 under the Symington amendment, which requires that the US not provide aid to countries possessing unsafeguarded nuclear technology and equipment. Congress restored aid in 1982 under a five-year waiver and was prepared to grant a two-year extension along with new aid.

But key lawmakers are ready to change their votes because of two criminal cases: the mid-July arrest of a Pakistani in Philadelphia for attempting to illegally export a special steel alloy used in nuclear weapons production and the July 17 indictment of a California couple for earlier exports of dual-use electronic equipment to Pakistan via Hong Kong.

Previous supporters of the new aid package, such as Rep. Steven Solarz (D) of New York, are reportedly convinced that Pakistan violated a 1985 law that mandates cutting off aid to a nonnuclear nation that tries to acquire illegally US materials or technology for producing nuclear weapons.

Despite Pakistan's vital role on Afghanistan, key lawmakers are saying that if Pakistan violated US law it must pay. One congressional critic complained, ``Pakistan has consistently violated all of its promises - public and private - on nuclear-weapons development. ... Now they are treating us with contempt.''

Administration spokesmen say they share that concern and want Pakistan to provide ``tangible evidence'' that its actions match its stated nonproliferation policy.

Pakistan's nuclear program is anchored in a deep-rooted fear of its neighbor, India. The countries have fought three wars since 1947. India has an advanced nuclear program and has exploded an atomic device.

A private US expert argues that Pakistan will probably not agree to limit its nuclear capabilities unless India does the same. He adds that India, for its part, is not likely to be interested in pulling in its nuclear horns unless China - its nuclear neighbor to the north - also signs on. And this is improbable, he says.

Pakistan has not exploded a nuclear device. But, this expert says, ``it has otherwise not slowed down its nuclear program'' and is believed to be ``a turn of the screw away'' from building a bomb. He adds that Pakistan has moved from securing the means to build a bomb to searching for ways to miniaturize the weapon and to enrich uranium more effectively. Pakistan has reportedly already enriched some uranium above the 90 percent level required for a bomb. ``In all of this the Pakistani line has been to categorically deny any wrongdoing,'' this expert notes.

Administration sources agree that the most troubling aspect of the Pakistani program is the uranium-enrichment plant at Kahuta. ``Their route to nuclear weapons is enrichment, and this could be only months away,'' if the word is given, a US official says. The problem is to ensure that they keep their enrichment only at levels needed for energy production (5 percent), and the best way to do this is with inspection of the Kahuta facility.

US officials say the danger of a break with Pakistan over its nuclear program is that Pakistan could slow the flow of aid to the Afghan guerrillas and agree with Moscow to accept the status quo in Afghanistan. ``Moscow may toughen up if it sees problems in US-Pak relations,'' an official says.

Officials add that, bereft of a supportive relationship with Washington, Pakistan would be tempted to push its weapons program, which in turn would strengthen the pro-bomb lobby in India. The result could be a full-scale nuclear arms race in South Asia, further undermining US interests there.

Undersecretary Armacost's mission in Islamabad is to avert these dangers. He will be searching for a solution that convinces Congress to approve new aid before the September arms cutoff deadline.

Key dates in US-Pakistan nuclear relations

April 1979. Carter administration cuts off aid to Pakistan under the Symington amendment because of unsafeguarded nuclear facilities.

December 1979. Soviet troops invade Afghanistan.

1981-82. Reagan administration negotiates a $3.2 billion, five-year aid program with Pakistan, including 40 F-16 aircraft. Congress votes a five-year waiver of the Symington amendment. Massive aid flows to the Afghan resistance through Pakistan. President Zia promises President Reagan that Pakistan is not interested in acquiring or making nuclear weapons.

February 1984. A Pakistani national is caught trying to export nuclear triggers from the US. Four months later two others are convicted in Canada for exports of nuclear-related, US-made electronics. The director of Pakistan's uranium facility at Kahuta says Pakistan has mastered the enrichment process and now has the development of a weapon within its means.

Summer 1984. The US queries China over reports that it provided a nuclear-bomb design to Islamabad.

Fall 1984. US intelligence reports allegedly say India is considering a preemptive strike on the Kahuta facility. After supportive US statements and a letter from President Reagan, Pakistan reportedly promises not to enrich its uraniun above 5 percent.

Fall 1985. American intelligence reportedly says that Pakistan has enriched uranium to 93.5 percent - 90 percent is considered weapons grade - and conducted a test to perfect a nuclear trigger.

1986. US negotiates a $4.02 billion, six-year aid package, which may include early-warning surveillance aircraft.

Spring 1987. Congressional committees agree in principle to the aid package and a new two-year extension of the Symington amendment.

July 1987. Two cases of illegal nuclear-related exports involving Pakistan spark congressional calls for aid cutoff.