Just when an Afghan plan looked near ...

As the talks on Afghanistan get under way in Geneva, the Reagan administration is facing a new potential battle front: Congress. Monday the Senate fired a strong salvo with 77 to 0 approval of a toughly worded resolution urging the administration not to be lulled into a bad agreement with the Soviets. An identical resolution has been introduced in the House. Supporters say it will be passed this week or next.

The administration was surprised by the Senate concern. Rumblings from the more conservative supporters of the Afghan resistance were expected, but when Senate Majority Leader Robert Byrd (D) of West Virginia took up the cause, the nature of the pressure changed.

Senator Byrd now says he wants to know what is in the still-secret accords, which are currently being negotiated under the auspices of the United Nations in Geneva, before he calls up the US-Soviet INF Treaty for ratification. He says the United States would be ``foolish'' to sign on to the accords until ``some very troublesome issues'' are settled and says the US would be ``dumb'' to rely only on Soviet promises.

Aides to Byrd say this is one of the ``few foreign policy issues that really move'' him and that he is sincerely worried that the Afghan resistance not be left adrift.

The administration recognizes this issue will require careful tending, officials say. Worried legislators say they want to be kept fully informed and consulted. Some say they will push for additional aid for the resistance if their concerns are not met, even over administration objections.

Many legislators have only recently begun to focus on US commitments under the Geneva proposals on Afghanistan. At first glance, many are concerned the US has agreed to imbalanced arrangements that will cut off US support for the Afghan resistance too early, while the Soviets would be free to continue supplying arms and advisers to their Afghan clients during and after their troops pull out.

Byrd warns that it is not wise to be under the pressure of a US-Soviet summit deadline to reach agreement on Afghanistan. He and other senators were not reassured by private briefings from Secretary of State George Shultz last week. ``The secretary came away from Moscow with gut feelings the Soviets are serious, but no specifics,'' says a key Senate aide.

Sen. Claiborne Pell (D) of Rhode Island, who chairs the Senate Foreign Relations Committee, and Rep. Stephen Solarz (D) of New York, who chairs the House subcommittee responsible for Afghanistan, are among those who think the administration is being tough and that the key is removing the Soviet troops.

``It's time to take yes for an answer,'' Representative Solarz says. ``If the Soviets are willing to leave Afghanistan, let's hold the door open for them.''

Under the current drafts of the accords, Washington would cut off all military aid to the resistance 60 days after the accords are signed and simultaneously with the beginning of Soviet troop withdrawal.

Critics say this will leave the resistance unsupplied during the 8- to 10-month Soviet withdrawal, while Moscow will be free to resupply its clients, keep thousands of military advisers in place, and launch attacks. The US would be hard pressed, the critics say, to restart the supply if the Soviets decide to reenter Afghanistan. Critics say such reentry is possible and could deal a severe blow to the guerrillas.

Administration officials reply that Soviet leader Mikhail Gorbachev has agreed to the principle of removing large numbers of Soviet troops in the first three months of a withdrawal, which they say, would make it very hard to launch offensives. Washington is also pressing Moscow to stop all military aid and withdraw military advisers as part of its commitments.

US officials stress they must be satisfied with specifics on the withdrawal of Soviet troops and its verification before the administration will commit to the agreement. They say that the resistance will be well-stocked with weapons and supplies at the cutoff date and humanitarian aid will continue after that.

The Associated Press reported yesterday that Pakistan had backed off from its demand for a transitional administration in Afghanistan to oversee a withdrawal of Soviet troops. Pakistan has in the past said it would not sign an agreement with the present Afghan government but only with a new ``legitimate'' government. It has wanted to avoid prolonged fighting and assure that the 3 million Afghan refugees within its borders will go home. But as Pakistani Minister of State for Foreign Affairs Zain Noorani sat down to begin talks with UN mediator Diego Cordovez, he told reporters: ``We will cross that bridge when we come to it.''