A Ukrainian army commander has stressed that his forces will keep fighting to retake the eastern part of the country occupied by Russia.
Colonel General Oleksandr Syrskyi posted comments on social media on Monday after his forces made gains in the key city of Bakhmut.
Syrskyi said the advancement of his troops is "the first success of offensive actions during the operation to defend Bakhmut." But he added that it is only a partial success.
Ukrainian Deputy Defense Minister Hanna Maliar also said on Sunday, "To date, our units have captured more than 10 enemy positions in the north and south of the outskirts of Bakhmut." She added that fierce fighting is continuing.
Russia's defense ministry said on Sunday two of their commanders were killed in a battle near Bakhmut.
It said one of them died after receiving multiple shrapnel wounds as his brigade tried to repel Ukrainian attacks.
The Institute for the Study of War reported on Sunday that Russian forces conducted another series of drone and missile strikes against Ukraine on the night of May 13 to 14. The US think tank said the drones were made in Iran.
It said, "Increasingly regular series of Russia drone and missile strikes are likely a part of a new Russian air campaign in Ukraine aimed at degrading Ukrainian abilities to conduct counteroffensive operations in the near term."
Meanwhile, Ukrainian President Volodymyr Zelenskyy arrived in London on Monday for talks with British Prime Minister Rishi Sunak.
The prime minister's office released a statement saying Sunak "will confirm the further UK provision of hundreds of air defense missiles and further unmanned aerial systems including hundreds of new long-range attack drones with a range of over 200 kilometers."
The statement also talks about the start of basic training for Ukrainian pilots "this summer," which will go hand in hand with the provision of F-16 fighter jets that Kyiv is demanding.
London announced on Thursday the provision to Kyiv of cruise missiles with a range of over 250 kilometers -- the longest among those pledged by Western allies.
Britain is set to further increase military support for Ukraine during Zelenskyy's current visit.