Near the eastern city of Avdiivka, recently captured by Russia after a fierce months-long battle, a regiment of Ukrainian sappers get to work on a network of trenches aimed at helping Kyiv's outgunned and outmanned army stymie the Russian advance. Besides the muddy trenches, the fortifications include anti-tank ditches and rows of pyramid-shaped concrete blocks called "dragons' teeth" for slowing down armoured vehicles. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES N°34PX3K6