Moving between damp basements and muddy dugouts to fend off constant Russian attacks in the nearly four-year-old war, exhausted Ukrainian soldiers say their motivation is fortified by knowing they're fighting for a higher cause: the defense of their homeland.

But as negotiators try to hammer out a peace deal, the troops also believe that Russia remains determined to conquer Ukraine — either now, or with a fresh army in a few years' time — no matter what kind of agreement is reached.

And they say Kyiv must maintain a sizable military to protect the now-800-mile (nearly 1,250-kilometer) front line.

“The armed forces of Ukraine are now the main barrier between peaceful civilian life of Ukrainians and our bad neighbor,” explained a 40-year-old artillery gunner who recently spoke to The Associated Press near the border between the Dnipropetrovsk and Donetsk regions.

The member of the Da Vinci Wolves Battalion identified himself only by his call sign of ”Kelt," in keeping with military protocol, and on condition his exact location was not revealed.

Soldiers like "Kelt" have expressed strong doubts that Moscow can be trusted to abide by any peace deal.

Without substantial security guarantees, such as NATO membership for Ukraine, they and military analysts believe a new Russian invasion with fresh troops and equipment is inevitable.

Serhii Filimonov, the commander of the Da Vinci Wolves battalion, worried that a deal would give Russia everything it needed to attack again.

Still, he believed his troops would be able to repel any advance.

“We cannot move forward, because we do not have enough people, but the line that we are holding now, we are holding quite confidently, and I believe that we can do this for a very long time,” he said.

Russian President Vladimir Putin said last week the fighting won’t stop unless Ukraine withdraws troops from the regions of Donetsk, Luhansk, Zaporizhzhia and Kherson — the four provinces Moscow illegally annexed in September 2022.

Russian troops occupy only half of Zaporizhzhia and Kherson, and two-thirds of Donetsk.

The draft of a U.S.-Russia peace plan stipulated that Ukraine’s army be limited and that Kyiv's forces must effectively withdraw from the rest of the Donetsk region.

Ukrainian President Volodymyr Zelenskyy has said since then that a subsequently revised version could be “workable,” but it's unclear what will be in the final document.

AP video by Vasilisa Stepanenko