The Hurt Locker and Obasan are as different as night and day when it comes to war, and I don't see many similarities regarding the destruction of war between them--at least the "destructive nature of war" is not a prominent theme for either.
Whereas The Hurt Locker is populated by male characters directly involved in war, Obasan focuses on female internment camp victims who are behind the lines. Ironically, the war brings the survivors of both works closer together, giving the main characters a better sense of identity. For James in The Hurt Locker, war is a thrill, a drug to which he is addicted; his duty calls him away from domestic life to the front lines of the war. For Naomi Nakane in Obasan, World War II is a disruption to her childhood, and it confuses her in terms of identity and femininity. While James knows he belongs in war, Naomi Nakane only understands the effects of the war later in life. Neither character moralizes about war.
Yes, both works show that war is destructive on multiple levels (such is the nature of war), but neither foregrounds the destruction at the expense of character identity. As both are realistic, war is almost taken for granted as a reality of the geo-political world, and neither author (or director) is overtly anti-war.
More importantly, Naomi Nakane looks to Obasan as a maternal paragon of steadiness and poise in the same way as Sanborn and Eldridge look to James as the unnerved hero of the squad. More than the destructive elements of war, both works focus on the strong, often silent, and certainly underappreciated heroes of the war.