BELARUS BORDER, UKRAINE • The reconnaissance drones fly several times a day from Ukrainian positions deep inside the thick forest that marches across the border into Belarus, a close Russian ally, scouring sky and land for signs of trouble on the other side.

Ukrainian units are monitoring the 650-mile frontier of marsh and woodland for a possible surprise offensive from the north, a repeat of the unsuccessful Russian thrust toward Kyiv at the start of the war nearly a year ago.

This time the Ukrainians are taking no chances. Since the summer they have been reinforcing defenses, building and expanding trenches and laying mines in the forest ahead of the springtime offensive military officials expect. Residents of villages in the region that were temporarily occupied last year are horrified by the prospect of it all starting again.

“We’re listening out for every small sound and noise. This isn’t a way to live,” said Valentina Matveva, 64, from the village of Ripky. “When you’re in constant fear, that’s not life.”

Concerns of a renewed military push were stirred in January after Russia and Belarus held joint air force drills, one month after a rare visit by Russian President Vladimir Putin to Minsk.

Military experts and Western intelligence have played down the possibility of a renewed northern offensive. The British Defense Ministry tweeted on Jan. 11 that Russian aircraft and existing Russian troops in Belarus, though numerous, are “unlikely to constitute a credible offensive force.”

Belarusian officials attribute the troop deployment along the border to “strategic deterrence” according to local reports. The country’s authoritarian president, Alexander Lukashenko, has insisted he will not send troops to Ukraine.

But Ukrainian commanders are wary, remembering how Russia used Belarus as a staging pad in early 2022.

“We continuously monitor the enemy from the ground and observe the movement of troops, if they are moving, how many troops, and where they are moving,” the area’s army intelligence unit head said during a press tour this week a few kilometers from the border. The officer only identified himself by his first name, Oleksandr, citing security reasons.

Unlike the east with its devastating artillery duels, here in the north it’s largely a war of quadcopters.

Oleksandr said the Belarusians and Russians are “constantly monitoring our guard changes, trying to find our military’s positions.”

At times, Oleksandr’s unit detects enemy reconnaissance drones and shoots them down using anti-drone rifles. Or an enemy drone detects a Ukrainian one and tails it, at which point the Ukrainians try to capture and add it to their stock.

“We got four of their drones this way recently, and they took two of ours,” Oleksandr said.

He says the reconnaissance missions have revealed no sign of worrying activity — yet. “They have a reinforcement section, and the patrol has been strengthened, but we do not observe a significant accumulation of troops from our section,” he said.