President Carter's strong talk in response to Moscow's conversion of Afghanistan into a Soviet satellite has fallen short, leading the government of Pakistan to question the wisdom of putting its fragile eggs in the American basket.

Skeptics in the Pakistani government are believed to include President Mohammed Zia Ul-Haq, a former army general with healthy respect for Soviet military might. To persuade him, Jimmy Carter must put teeth into his words. Tough talk followed by empty threats has characterized his foreign policy for three years, a fact well known by every country exposed to Soviet power.

Although the Soviet invasion started Dec. 24, Carter has been slow to announce concrete actions other than sending a diplomatic mission to Western Europe and complaining to the United Nations. "Zia is sitting in a country totally exposed to Soviet power." One foreign diplomat told us. "He needs proof that the U.S. will sustain him for the long haul, but all he has are words and consultations."

What Zia wants to deeds: a hard dollar value on immediate U.S. military aid; U.S. sale of arms to Communist China, which more than anything else would signal the reality of Carter's professed fury at Moscow; U.S. aid to the nearly half-million Afghan patriots now in hiding across the Pakistani border. On top of this shopping list, an admission that this is no time to push SALT II would signal that Carter means business.

In the absence of such signals, Soviet propanganda blasts at Pakistan have escalated. First came low-level complaints that the Paks were allowing Afghan rebels to use bases along the border to attack the pro-Soviet government in Kabul. Now there is a full-fledged charge of cross-border raids by "imperialist" agents in Pakistan trained by the CIA.

Begun by vagrant radio broadcasts, this noxious accusation is now cloaked in the authority of Pravda and Izvestia, reflecting highest Soviet policy. The Kremlin, therefore, could be building a case for cross-border action into Pakistan.

To President Zia's government, this verbal escalation stems partly from the West's -- especially Washington -- failure to react with specific deeds to the Soviet takeover of Afghanistan.

U.S. delay breeds more delay. Robert F. Goheen, the U.S. ambassador to India, has rushed home to counsel caution in helping Pakistan; to do so will cause terrible trouble with India, already in Moscow's embrace. With good cause, Pakistan credits India with immense influence in the Carter administration.

If Jimmy Carter had no three-year record open to inspection, Pakistan and other weak states within reach of the lengthening Soviet grasp might believe he means business. Why else would the president agree with ABC interviewer Frank Reynolds that Soviet President Leonid Brezhnev is a liar?

Carter's record suggests something different. During a spasm of anger last fall when a Soviet combat brigade was discovered in Cuba, Carter told congressional leaders he could not accept the Soviet explanation. "They're lying," he said. Six days earlier, he had used similar language inside the White House, claiming "they lied to us" in denying the existence of the brigade.

That tough talk was followed by quiet acceptance of the brigade. President Zia and leaders of other weak countries menaced by Moscow took note.

After Carter's virtuoso perfomance obtained an Istaeli-Egyptian peace agreement, he repeatedly informed the world that Israel had agreed to create no new-settlements on the West Banks. Israeli Prime Minister Menachem Begin said the president was wrong. New settlements have continued ever since.

More recently, The Washington Post disclosed that the Carter administration tried to bluff Chile into extraditing three intelligence officers wanted here for trial in a political assassination. The bluff failed. A high ranking U.S. diplomat in Santiago was quoted by The Post: "They called our bluff and we lost."

It is no surprise, then, that Pakistan wants not only strong talk from Washington but supply of arms against the Soviet advance. Some U.S. officials here believe Carter intends to do just that. But the Zias of this world need proof, and soon.