WASHINGTON, Nov. 3 - Russia's border with eastern Ukraine has softened to the point of becoming completely porous, while an internal Ukrainian dividing line hardens, NATO's top general said on Monday, cautioning about the risk of another "frozen conflict," Reuters reported.

U.S. Air Force General Philip Breedlove, NATO's supreme allied commander Europe, said he believed there were about 250 to 300 Russian troops inside eastern Ukraine helping train and equip Russian-backed forces.