Hands on his machine gun, a young Ukrainian soldier scans the steppe from his shelter, a few hundred meters from pro-Russian separatist positions. Despite the apparent calm, he remains vigilant, saying "we will push back the enemy," as Kiev and the West worry about a possible new Russian offencive. Western countries have this month raised alarm over reported Russian military activity near Ukraine, with the United States saying it has "real concerns" over a new troop build-up on the border. IMAGES AND SOUNDBITES