Soviet ground forces, assisted by airborne troops, have pushed well over halfway through Afghanistan's strategic Panjshir Valley, Western diplomatic sources confirmed this week.
They conceded, however, that they were receiving highly contradictory accounts on whether additional airborne reinforcements had arrived and secured the crucial Anjuman Pass. Reports from Afghan resistance sources in Peshawar, Pakistan, over the weekend claimed the Soviets had blocked the northern route into the valley by securing the northeastern pass.
According to the Western sources, the Soviets, in their largest offensive in the 41/2-year-old war, appear intent on encircling the valley. It is the stronghold of one of Afghanistan's most renowned guerrilla fighters, Ahmed Shah Massoud - the only resistance leader with whom the Soviets have ever negotiated. Last January, the two sides entered into a year-long truce.
The scope and intensity of the Soviets' Panjshir offensive and the Soviets' dogged effort to capture Mr. Massoud, add credence to reports of a decided hardening in the Kremlin's Afghanistan line since the accession of Konstantin Chernenko in February of this year.
Yuri Andropov had hinted he was interested in a negotiated solution to what some in the Kremlin have conceded was a vexing foreign war.
All indications from the Kremlin now, however, are that Mr. Chernenko is not.
''In short,'' said an Eastern diplomatic official, ''Andropov gave high priority to the United Nations-sponsored talks. We've seen during the April visit of (the UN mediator, Diego) Cordovez, that Mr. Chernenko is not at all interested in a Soviet withdrawal . . . and he isn't because, despite the conventional wisdom that has coalesced the West, the new Soviet leadership does not believe that its Army is bogged down in Afghanistan. . . .''
''Time and resources are clearly on the Soviet side,'' he continued. ''For a very limited investment, they have made significant geopolitical gains.''