"This is another XXX" never means thatbvisit is indentcal. Just that in certain important ways it is similar. This is one unholy mess of a foreign war that America (and this time a few camp followers) has got itself tied into. That's enough to justuify the expression.

Obviously it's different in a lot of ways. In fact in some ways it is much more of a mess. Vietnam was a foreign war for the USA, in one corner of the world. This time it is likely to end up a much more dispersed operation, with a strong domestic component.