WASHINGTON, Dec. 12 - The Pentagon is engaged in bitter, high-level debate over how far it can and should go in managing or manipulating information to influence opinion abroad, senior Defense Department civilians and military officers say. Such missions, if approved, could take the deceptive techniques endorsed for use on the battlefield to confuse an adversary and adopt them for covert propaganda campaigns aimed at neutral and even allied nations. Critics of the proposals say such deceptive missions could shatter the Pentagon's credibility, leaving the American public and a world audience skeptical of anything the Defense Department and military say...