Russia's complex defenses are a brutal test for Ukrainian troops' close-quarters-combat skills

• Ukrainian forces have been battling entrenched Russian troops in eastern and southern Ukraine.
• Russia's extensive fortifications force Ukrainians to fight through minefields and into trenches.
• A recent video shows Ukrainian troops using close-quarters-battle skills inside a Russian trench. 

Ukraine launched its long-awaited counteroffensive against Russian forces in the eastern and southern parts of the country in early June. While Ukrainian troops are making progress, they are not moving as quickly as Kyiv and its Western partners had hoped.