Russian jets, some flown by Wagner mercenaries, are making risky attacks to test Ukraine's defenses around Bakhmut

• Ukraine and Russia are fighting a grinding battle on the ground around Bakhmut.
• Russian aircraft, some operated by mercenaries, are also being used in fighting around the city.
• Those jets are used sparingly and often at night, likely to test Ukraine's defenses, an expert said.

After months of struggling to capture the Ukrainian city of Bakhmut, Russian ground troops still haven't been able to wrest all of the city away from tenacious Ukrainian defenders.

One reason is lack of air support. Despite large numbers of advanced aircraft and munitions, Russian airpower has proven marginal in Ukraine, where the battles have mostly been between infantry, tanks, and artillery.