I'd prefer warfare to be the master tag, but that's not really important.
My initial response would be no. war is used for questions about specific wars. Why did Operation Market Garden go ahead when the allies knew German armor was in the area? How did Israel win the Six-Day War? warfare is used for more general questions. Did World War II-era bombs actually whistle? How frequently were homing pigeons used in the World Wars? More general questions about how war is waged. I can't say this rule is always followed or that the tags have clear wikis, but that is how I see it as a general rule.
I would rather establish firmly the distinction than to synonymize (is that a word?) them. A similar confliction of tags is https://history.meta.stackexchange.com/q/171/961, which was declined. Although they were not being used correctly at the time, they are now clearly separated. In fact, after writing up this answer, I believe warfare and military should be synonyms. Writing another meta discussion...