Russian forces are building new defensive positions miles behind the current front lines of the Ukraine war, according to Britain’s defense ministry, indicating that they may be planning further retreats in the face of Ukrainian advances.

After Russian President Vladimir Putin’s defense chief ordered a retreat across the Dnipro (also known as Dnieper) River, Ukrainian troops entered the southern city of Kherson last week. The capture of Kyiv, which had been under Russian occupation since the beginning of the war, came after Russian losses in the northeast and represented a massive battlefield humiliation and defeat for Moscow.

Britain’s defense ministry stated in a Friday intelligence update that after Russian forces withdrew from Kherson, they prioritized reorganizing, refitting, and assuming defense preparations across various areas of eastern and southern Ukraine still controlled by Putin’s occupying troops.

“Units have built new trench systems near the Crimean border, as well as near the Siversky-Donets River between Donetsk and Luhansk Oblasts” in eastern Ukraine, according to the ministry. “Some of these locations are up to 60 kilometers [37.3 miles] behind the current front line, indicating that Russian planners are preparing for additional major Ukrainian breakthroughs.”

In recent months, Kyiv’s forces have made significant advances, launching counteroffensives along the war’s northeastern and southern fronts. As a result, they have retaken control of major cities such as Kharkiv in the northeast and Kherson in the south, as well as liberated thousands of square miles of territory throughout the region.

According to Britain’s defense ministry, Russia is likely to try to redeploy some troops from the Kherson withdrawal to support an offensive near Bakhmut, a city of over 70,000 people in eastern Ukraine’s Donetsk region.

According to a recent assessment by the Institute for the Study of War in Washington, Russian forces have continued to attack Bakhmut, though Ukrainian forces have so far managed to repel the assaults. In a speech last weekend, Ukrainian President Volodymyr Zelenskyy stated that Russian attacks in the Donetsk region have turned violent.

“Every day, there are extremely brutal battles. But our units defend themselves valiantly, enduring terrible pressure from the occupiers and maintaining our defense lines. It is extremely important. We can conduct offensive operations in other directions because of the strong defense in the Donetsk region “According to Zelenskyy.

In the midst of these developments, tensions have risen this week after an explosion was reported in eastern Poland, just over the shared border with Ukraine, marking the first time that Russia’s unprovoked war has spilled into NATO territory.

The incident sparked panic among some military alliance officials, as well as top Ukrainian leaders such as Zelenskyy and Foreign Minister Dmytro Kuleba, who blamed the deadly blast on Russia. Western leaders, including NATO leaders, have suggested that the incident was unintentionally caused by a Ukrainian surface-to-air missile defending the country against a barrage of Russian strikes earlier in the week.

“Our preliminary investigation indicates that the incident was most likely caused by a Ukrainian air defense missile fired to defend Ukrainian territory against Russian cruise missile attacks,” NATO Secretary General Jens Stoltenberg said on Wednesday. “But let me clear,” he continued, “this is not Ukraine’s fault. Russia bears ultimate responsibility as it continues its illegal war against Ukraine.”

Ukraine has so far rejected these assessments, insisting that it be a part of further investigations into the incident.