NEW : NATO chief says he ca n't confirm Russian withdrawal from area bordering Ukraine . Russia says one battalion is being pulled back from border region after finishing drills . U.S. officials say Russia may have as many as 40,000 troops near its border with Ukraine . Additional intelligence indicates that even more Russian forces are `` reinforcing '' the border region , according to U.S. administration officials , and all of the troops are positioned for potential military action . Comment:
NEW : NATO chief says he ca n't confirm Russian withdrawal from area bordering Ukraine . Russia says one battalion is being pulled back from border region after finishing drills . U.S. officials say Russia may have as many as 40,000 troops near its border with Ukraine . Comment: