KYIV/LONDON, May 19 - From burning oil refineries to a stalling ground offensive, Russia is suffering problems in its war against Ukraine that partly stem from a growing Ukrainian military strength: the use of medium-range drone attacks. Read more at straitstimes.com. Read more at straitstimes.com.

May 14 - Ukraine has stepped up drone attacks on Russia's energy infrastructure, doubling the number of oil refineries targeted since the start of the year, according to information posted on social media by Russian officials. Read more at straitstimes.com. Read more at straitstimes.com.

May 14 - Ukraine has stepped up drone attacks on Russia's energy infrastructure, doubling the number of oil refineries targeted since the start of the year, according to information posted on social media by Russian officials. Read more at straitstimes.com. Read more at straitstimes.com.