Lieut. Col. Javier Carrion, the regional Sandinista commander, said he knew of no border crossings by his troops.

Sandinista commanders wanted to attack before something happened that could reinvigorate the contras.

The Sandinista commanders say they have tried to wage a humane revolution - and by any standard theirs has not been a notably bloody effort to bring social change.

In 1982 he turned to the charismatic Edén Pastora, the former Sandinista commander starting up the rebel Democratic Revolutionary Alliance, only to become disenchanted with him as well.

The defeated Government's opponents complain that Sandinista military commanders are now in charge of the police in many areas and continue to harass them.

The shift in popular outlook may have been made possible by the division of powers among the Sandinista commanders after their electoral defeat.

The Sandinista commander in the area sent out units to ambush the returning contras and to determine the location of their headquarters.

But the rebels do not at present seem to be the "strategically defeated" force that top Sandinista commanders have tried to depict.

"It's a very professional operation run by the C.I.A. and we haven't been able to stop it," a senior Sandinista commander said.

Mr. Ruiz, one of nine ruling Sandinista commanders, said some donor countries have complained that Nicaragua does not efficiently use the aid it receives.