Since Russia launched its full-scale invasion, partly from the territory of Belarus, Ukraine has handled relations with its northern neighbor cautiously. It did not sever diplomatic relations and kept open lines of communication with President Aleksandr G. Lukashenko, Belarus’s longtime autocrat.

But since the beginning of this year, after a string of devastating Russian drone strikes in northwestern Ukraine near the border with Belarus, President Volodymyr Zelensky has taken a more confrontational approach.

He ordered strikes early in the year against four signal relay stations in Belarus that, he says, are being used by Russia to direct drone attacks on Ukraine. In May he invited Belarus’s exiled opposition leader, Svetlana Tikhanovskaya, to open an office in Kyiv. And last week he threatened publicly to attack the relay stations in Belarus again.

“Let him take down this equipment,” Mr. Zelensky said of Mr. Lukashenko. “Because right now, every day, our civilians are dying and children are being injured because of this. If he doesn’t do it, we will.”

On Thursday, Mr. Zelensky said the relay stations had been turned off, for now.

Western diplomats and analysts have interpreted Mr. Zelensky’s threats as part of a more aggressive attitude toward his neighbor, bolstered by the success of Ukraine’s campaign of long-range attacks on Russia’s oil industry.

“The current dynamics are more an evolution of Kyiv’s emerging regional posture than a response to an immediate military threat from Belarus,” Balazs Jarabik, a former Slovak diplomat, wrote in a commentary for the Carnegie Endowment for International Peace.

But Ukrainian officials and analysts said Mr. Zelensky was motivated by ongoing attacks from Russian drones, which were directed by relay stations, known as repeaters, in Belarus, severely stretching Ukraine air defenses as the war escalates on several fronts.

“Ukraine, defending its interests, cannot ignore the deployment of things like repeaters,” Yaroslav Chornohor, Ambassador at Large of the Ukrainian Ministry of Foreign Affairs, said in an interview. “Turning a blind eye is no longer an option.”

Russia’s use of drone relay stations in Belarus has been going on for months, Mr. Chornohor and other officials said. From December Ukraine has suffered a string of attacks on its railways, in particular on a rail line running from the Polish border to Kyiv, a critical logistics route.

Ukrainian Railways reported several attacks by Russian Shahed drones on a cargo train, a locomotive depot and a bridge on the Kovel-Kyiv line. Drones also hampered rescue efforts, the railway company said.

In March there were three more strikes on the same rail line and in April a woman was killed in a strike on a train, according to the regional governor.

In June, Russia unleashed a devastating attack on Korosten, the main depot on the Kovel-Kyiv line, according to Vitalii Kulyk, head of the Center for Civil Society Research, a research organization that works on civil-military subjects.

“In just one locality, Korosten, close to 20 locomotives were destroyed in just one week in June, practically halting operations,” Mr. Kulyk said in an interview.

“Such pressure on border transport infrastructure aims to sever our primary supply artery leading from western Ukraine to the front line,” he said. “It has evolved into an issue of critical security importance, which is why it was brought to the forefront.”

The severity of Russian attacks in Ukraine is often underreported, since officials often hold back details for reasons of security.

But Serhii Beskrestnov, a technical adviser to Ukraine’s Ministry of Defense, has been writing on his Facebook page about the strikes since soon after the first attacks in December.

The drones were entering Ukraine directly from Russia, he said, but he noticed they were not homing in on preset coordinates, as they usually do, but were instead being directed manually to their targets.

“We are talking about remote control systems for Shaheds via radio channels through a so-called mesh network,” he said. “Control points are built on towers. When a Shahed flies deep into Ukrainian territory, it maintains a constant radio connection with these control points.”

The control points were relay stations in Belarus, he worked out.

“It is direct proof contradicting Belarus’s claims of being a neutral country,” Mr. Beskrestnov said.

He said he saw for himself how the Shaheds could be directed in April, when his house came under attack. As he took cover, he watched the drones circling and maneuvering before hitting the building, he said.

“When they attacked my house, there were five jet powered Shaheds with online control, operated from Russian territory,” he said.

Belarus was providing roaming facilities from its mobile telecommunication towers to the Russian drones, which were equipped with modems and Russian SIM cards, he said. This was allowing operators in Russia to direct the Shaheds and to transmit back reconnaissance data from their flights over Ukraine, he said.

After the drone attacks in December, Ukraine hit back, targeting several relay stations in Belarus. Mr. Lukashenko, who denies providing assistance to Russia, protested, but the strikes brought a reprieve for Ukraine, Mr. Chornohor said.

But after a while the attacks resumed.