The Ukrainian soldiers rose in the predawn, stretching, rubbing their eyes and rolling up sleeping bags in a basement hide-out near the front line in the country’s east. Their day would not take them far afield: Most stayed in the basement, working with keyboards and joysticks controlling drones.

At a precarious moment for Ukraine, as the country wobbles between hopes that President Trump’s cease-fire talks will end the war and fears that the United States will withdraw military support, the soldiers were taking part in a Ukrainian Army initiative that Kyiv hopes will allow it to stay in the fight absent American weapons.

On Sunday, after a week of unabated warfare in Ukraine, including the deadliest attack on Kyiv, the capital, in nearly a year, the Trump administration issued somewhat conflicting signals about what would come next. President Trump had a short meeting with President Volodymyr Zelensky of Ukraine over the weekend that Mr. Trump said went well, and in later comments he did not rule out sending more weapons. But Secretary of State Marco Rubio warned that the United States was close to walking away from the peace table and said that the coming week would be “very important.”

Should the peace talks fail, or the United States decide to discontinue arms shipments, the Ukrainian drone initiative is likely to take on more importance than ever. The program, called the Line of Drones, doubles down on unmanned systems that are assembled in Ukraine, mostly small exploding drones flown from basement shelters.

The program is a reminder, once again, of Ukraine’s ability to innovate during this war, which has helped it face off against its much larger enemy.

“It’s not man against man anymore,” said the commander of the squad operating from the basement in eastern Ukraine.