KYIV, Ukraine — A monthslong border blockade by Polish truckers is starting to affect Ukrainian soldiers in frozen trenches defending against unrelenting Russian assaults, making already fierce battles even more difficult.

One Ukrainian soldier, Oleksandr, fighting in eastern Ukraine, said his unit was still waiting for delivery of two night-vision devices, critical for soldiers navigating their way to fighting positions safely. The equipment has been held up at the border, he said, where Polish truckers have blocked major crossings, causing backups miles long, since Nov. 6.

Oleksandr, who asked to be identified by only his first name in accordance with Ukrainian military protocol, was scathing about the action. “To block the borders of the country, during a full-scale invasion, they have to be completely detached from reality, and this way they also wash their hands in the blood of people who are waiting for the necessary help,” he said.

As of Wednesday, there were an estimated 2,950 trucks stranded on both sides of the Polish border, 650 at the border with Slovakia and 750 waiting to enter Ukraine from Hungary, according to Ukrainian officials.

Ukraine and Poland agreed to open a checkpoint Monday for a handful of trucks leaving Ukraine. But Poland, along with trucking associations from several other countries, is still calling on the European Union to restore a permit system for Ukrainian drivers that ended after the invasian.

Polish and Ukrainian officials said Thursday they had agreed to meet Friday behind closed doors to negotiate and see if they can find a way to end the blockade.

The dispute that led to the blockade appears simple: Polish truckers are upset about cut-rate competition from Ukrainian drivers who are not subject to the same rules on working hours and wages as drivers from the European Union. The Poles also say they are treated unfairly by Ukrainian customs officials who make them wait, giving Ukrainian drivers preference.

But as the blockade drags into a second month, the inability of Brussels to address the issue has been compounded by the internal politics of Ukraine and of its neighwbors; aggressive Russian propaganda; divergent business interests; and, increasingly, bitter emotions.

Rather than nearing a resolution, the blockade is expanding.