without him. >> reporter: anna cabrera, cnn, darrington, washington. tensions are mounting in ukraine. u.s. officials say as many as 40,000 russian troops are positioned near its border with ukraine. those troops and russia's recent annexation of crimea are sparking fears of a further incursion into ukrainian territory. president obama spoke about his concerns over this russian military buildup. >> you've seen a range of troops macing along that border under the guise of military exercises, but these are not what russia would normally be doing, and, you know, it may simply be an effort to intimidate ukraine or it may be the big additional plans. >> cnn's carl penhal is near the