Men wage war physically because they are physically stronger. Women wage psychological war. Women also prefer powerful men, forcing men to 'prove' themselves, ultimately chosing alphas.
Men are more involved, but women are at the root cause of violent acts. Most men are not violent and given time, violent men will be rooted out by brainy meeks. It is women who chose to copulate with violent men than the meek ones.
It is a very bad statement to say 'why men love war', and is only an insidious way of saying the patriarchal statement that 'loving war is manly'. To be expected in 1984, but not today.