ISLAMABAD, PAKISTAN -- In a turnabout in negotiating strategy, Pakistan is demanding agreement on the make-up of a new Afghan government as part of any negotiated settlement of the eight-year-old war in Afghanistan.

Until a few months ago, U.S. and Pakistani diplomats argued that the only outstanding issue in long-running U.N.-sponsored negotiations was Moscow's agreement to a rapid pullout of its 115,000 to 120,000 troops in Afghanistan. All other issues, it was argued, would take care of themselves once this question was settled.

It was Moscow that long appeared to link the pullout to an internal political framework, insisting on the dominance of the Soviet-backed People's Democratic Party of Afghanistan, led by Najibullah.

In recent months, however, Moscow said it could withdraw its troops in as little as 12 months, drawing close to the Pakistani, and U.S., negotiating positions on that issue. The Kremlin also appeared to drop its demand that a settlement include an agreement on a domestic Afghan political arrangement.

Now, Pakistan -- which plays a key role as the supply route and sanctuary for the Afghan guerrillas fighting the Soviet and Afghan government forces -- has relinked the pullout to an internal political arrangement.

President Mohammed Zia ul-Haq said last week, in an interview that appeared in The Washington Post, that he would not sign a settlement pact with the Soviet-backed Afghan leader, Najibullah. He called for an interim government, possibly including representatives of Najibullah's ruling party, saying that "all factions of Afghans must get together."

Zia's new emphasis on the need for an agreed interim government for Afghanistan may be a complicating factor in the negotiations at a time when hopes for progress appear high. According to different assessments here, the Pakistani stance could represent a recognition of political realities, or a dangerous effort to put more pressure on Moscow.

One diplomat who has followed the process closely suggested that as an accord became feasible, the Pakistani government began to look in detail at the implications of the existing negotiating goals. The diplomat said Zia's government may have become fearful that the guerrillas, and an estimated 2 to 3 million Afghan refugees in Pakistan's border areas with Afghanistan, might refuse to cooperate -- deciding instead to remain in Pakistan.

"Zia is concerned first and foremost about one thing, the stability of Pakistan," the diplomat said. He suggested that Zia's government fears any negotiated settlement that risks internal chaos in Afghanistan because such instability could easily disturb Pakistan's own delicate political balance.

Other observers argue, however, that Pakistan is raising the issue of the future Afghan government in an effort to influence its structure and win some lasting sway over Afghan affairs.

These two interpretations have highlighted signs of a split among Pakistani decision makers, according to foreign observers here.

One argument heard behind the scenes in Islamabad is that the government is giving too much attention to the Afghan guerrilla organizations based in the country. Observers holding this view say that Pakistan would find it difficult to maintain influence over the Afghan guerrilla leaders through whom they might hope to have a future role in Afghanistan.

According to one knowledgeable source, backed up by public statements from Afghan guerrilla leaders, the rebels have been pressing for a dominant role in a future Afghan government. Guerrilla domination of a future Afghan government is said to be appealing to some Pakistanis, who see the ties they have built up during the eight-year clandestine war giving them influence after Soviet troops leave.

Now that talks over Afghanistan are reaching a crucial stage, forceful arguments are heard here that Pakistan should not reach for long-term influence with a future Afghan government by insisting on a voice in formulating it.

One prominent observer argued against such a policy, which he said would operate at the behest of the Afghan guerrillas: "Who are they to tell Pakistan what to do? They are not a government. They are on our soil. Does this mean we surrender the sovereignty over what agreements are arrived at to get their return?"

"We should not be worried about the future of Afghanistan. We should only be worried about getting the Russian troops out. If they go out and there is a civil war that lasts for five or seven years, so be it. It is not Pakistan's problem."

According to this observer, Pakistan must decide its political goal in the negotiations. "Is it to get the withdrawal of Soviet forces and a guarantee of no outside interference in Afghan affairs, or is it putting the right regime in the saddle in Kabul?" he asked.

For some analysts here, Pakistan's new requirement for an interim government in Afghanistan poses a risk that the diplomatic process could collapse. "There is a real danger in letting the opportunity go by. It may not come up again -- not for a long time," said one close observer of the talks.

The conflicting pressures are believed to be weighing heavily on Zia as reflected in recent public statements, according to analysts here.

Early in January, when Zia reiterated in an interview with The New York Times that Pakistan favored a compromise government in Kabul that includes elements of the Afghan communists, it was viewed as a signal to Moscow that he was ready to bargain and a sharp public notice to the guerrillas, or mujaheddin, that they must prepare to deal with the communist People's Democratic Party, although not with its leader, Najibullah.

A week and a half later, in the interview published in The Post, Zia appeared to harden his stance by insisting on an interim government in Afghanistan before the signing of any settlement. That statement was published just as U.N. special negotiator Diego Cordovez was ending his first round of talks in Kabul.

"That set the cat loose among the pigeons," said one western diplomat.