Some Russian troops in Ukraine have surrendered en masse or sabotaged their own vehicles to avoid fighting, a senior Pentagon official said.

Some entire Russian units have laid down their arms without a fight after confronting a surprisingly stiff Ukrainian defense, the official said.

A significant number of the Russian troops are young conscripts who are poorly trained and ill-prepared for the all-out assault.

Also, in some cases, Russian troops have deliberately punched holes in their vehicles’ gas tanks, presumably to avoid combat, the official said.

Besides dealing with shortages of fuel, food and spare parts, the Pentagon official said, Russian commanders leading the armored column toward Kyiv may also be “regrouping and rethinking” their battle plans, making adjustments on the fly to gain momentum for what U.S. intelligence and military officials say is an inevitable push in the next several days to encircle and ultimately capture the capital.