Ukraine's forces retook the Kyiv region and northern areas of the country Saturday after Russian troops pulled out, leaving behind landmines and a trail of bodies, per Ukrainian officials and multiple reports.

The latest: Putin's forces appeared to shift their focus away from Ukraine's capital toward the south and east of the country, with Russia's military striking an oil refinery and fuel storage facilities in the key port city of Odessa on Sunday morning.

• Ukrainian President Volodymyr Zelensky said in a televised address late Saturday he was aware that Russian forces had "reserves to increase pressure in the east," but Ukraine was "strengthening our defenses" in the region and in Donbas in particular.

State of play: Zelensky said Russian forces had shelled in and around Kyiv and Chernihiv as they withdrew, but Ukrainian forces had retaken the region.

• Large civilian death tolls and severe damage were reported in the Kyiv region towns of Irpin and Bucha after Russian troops left.
• A Red Cross convoy that's attempting to evacuate Mariupol residents had still to reach the besieged southeastern port city, but some civilians had fled in private vehicles, AP reports.

Meanwhile, the U.K. Ministry of Defense said in an intelligence update late Saturday that there had been a "concentration of air activity" toward southeastern Ukraine in the past week, "likely a result of Russia refocusing its military operations in this area.

• The defense ministry said in a Sunday morning intelligence update that Russia's navy was maintaining a "distant blockade" of the Black Sea and the Sea of Azov, preventing Ukraine access to water supplies.

What to watch: "Despite ongoing Russian efforts to diminish Ukrainian air defence capability, Ukraine continues to provide a significant challenge to Russian Air and Missile operations. As a result, Russian aircraft are still vulnerable to short and medium range air defence systems," the defense ministry said.

• "Russia's inability to find and destroy air defence systems has seriously hampered their efforts to gain broad control of the air, which in turn has significantly affected their ability to support the advance of their ground forces on a number of fronts," the report added.

Editor's note: This article has been updated with comment from the Odessa regional military administration official and the U.K. Defense Ministry's Sunday intelligence update.