Ukraine's army said Friday it has suffered more losses in the fight against pro-Russian insurgents in the east as tensions in the three-year conflict simmered. The latest deaths were announced as US Secretary of State Rex Tillerson said he would be holding talks with Nato allies in Brussels about Russia's "aggression" in Ukraine. Two Ukrainian servicemen were killed and 13 others injured over the past 24 hours when their positions came under rebel fire, the Ukrainian military said in a statement. The deaths bring the military casualty toll to eight since the start of the week.