Johnson makes surprise visit to Kyiv, holds talks with Zelensky.

"This is a ticking time bomb and I think everybody in shipping knows it," shipping executive Alexander Saverys told the Financial Times.

With Ukrainian forces regaining the battlefield initiative, Kyiv has until winter to effectively negotiate with Moscow, Zelensky told CBS News in a May 31 interview.

"The evidence identified at the scene is structurally and functionally identical to those recovered... in previous incidents involving Geran-2 type unmanned aerial vehicles," the country's Defense Ministry said.

"The strike locations are situated at the junctions of major railway lines and road networks. In other words, the attacks targeted key logistics hubs where the enemy had been concentrating personnel and resources for further offensive operations," the 413th Regiment of the Unmanned Systems Forces said.

"Luhansk, Starobilsk, Alchevsk, Brianka, and Kadiivka are now under the control of the Third Army Corps' unmanned aerial vehicles (UAVs)," Brigadier General Andrii Biletskyi said.

Alexander Lukashenko also downplayed the capabilities of Ukrainian troops stationed along the Belarusian border, describing them as "cannon fodder."

In the latest episode of Ukraine This Week, Anna Belokur explains how mobilization actually works in Ukraine — and why the reality is far more complicated than viral videos often suggest.

Ukrainian forces hit the Saratov oil refinery, along with several other Russian oil industry facilities, overnight on May 31, the General Staff confirmed.

Russia launched 229 drones, 212 of which were intercepted by Ukrainian air defenses, according to the Air Force.

Russian forces launched more than 2,300 attack drones, nearly 1,560 guided aerial bombs, and 108 missiles over the past week, according to President Volodymyr Zelensky.

The number includes 1,560 casualties that Russian forces suffered over the past day.

The latest measures come as the peninsula continues to experience fuel shortages stemming from a combination of Ukrainian strikes on supply routes as well as on oil infrastructure.