VIETNAM has been the defining issue for John Kerry. His status as a decorated war hero has helped to propel him to the front of the pack of Democrat candidates seeking to evict George W.Bush from the White House. Conservative critics believe he has been given a free ride for too long on his war record, however, and are planning a fightback. Support for their case is expected to come from a book to be published next month by reporters from The Boston Globe in Kerry's home state of Massachusetts. The book, JF Kerry, the Complete Biography, will question the...