I agree with Mauricio's interpretation, which is the correct one, but also agree with Nathaniel's sense of ambiguity. With "war" being inanimate, we cannot normally expect it to be indifferent toward us, unless it is personified.

In an "X es indiferente a Y" structure, the usual interpretion is "X is indifferent to Y", but I think it is also possible to interpret it as "Y is indifferent to X." This ambiguity will arise when X is animate or personified, for example:

1. La muerte me es indiferente.

(1) will usually mean "I don't care about death," but it can also mean "Death does not pay attention to me."

With animate subjects, the ambiguity is stronger:

2. Juana me es indiferente (Juana es indiferente conmigo/hacia mí -- Juana is indifferent to me or Siento indiferencia hacia Juana -- I am indifferent to Juana).

Grammatically, "me" is an indirect object. According to item 35.3.1j of RAE's NGLE:

[...] los complementos argumentales de ciertos adjetivos se manifiestan sintácticamente como pronombres dativos que inciden sobre todo el grupo verbal, a veces en alternancia con otros predicados. Se obtienen así pares como Me es útil = Me sirve; No me es posible ir = No puedo ir.

The structure above also occurs with other verbs like estar, parecer, resultar.

Now, where does the ambiguity stem from? It lies in the meaning of "indiferente". Unfortunately, once again RAE's dictionary is not thorough enough. In the Free Dictionary, we find two possible acceptations for this adjective which are related to the case at issue:

3. Que no despierta deseo, afecto o interés en otra persona Él y su compañero me son indiferentes.
4. Que no se emociona, apasiona o conmueve Es indiferente a la miseria.

(3) would apply to the case of Juana not arousing my interest, and (4) to the case of "I" feeling indifference or apathy toward Juana.

I agree with Mauricio's interpretation, which is the correct one, but also agree with Nathaniel's sense of ambiguity. With "war" being inanimate, we cannot normally expect it to be indifferent toward us, unless it is personified.

In an "X es indiferente a Y" structure, the usual interpretation is "X is indifferent to Y", but I think it is also possible to interpret it as "Y is indifferent to X." This ambiguity will arise when X is animate or personified, for example:

1. La muerte me es indiferente.

(1) will usually mean "I don't care about death," but it can also mean "Death does not pay attention to me."

With animate subjects, the ambiguity is stronger:

2. Juana me es indiferente (Juana es indiferente conmigo/hacia mí -- Juana is indifferent to me or Siento indiferencia hacia Juana -- I am indifferent to Juana).

Grammatically, "me" is an indirect object. According to item 35.3.1j of RAE's NGLE:

[...] los complementos argumentales de ciertos adjetivos se manifiestan sintácticamente como pronombres dativos que inciden sobre todo el grupo verbal, a veces en alternancia con otros predicados. Se obtienen así pares como Me es útil = Me sirve; No me es posible ir = No puedo ir.

The structure above also occurs with other verbs like estar, parecer, resultar.

Now, where does the ambiguity stem from? It lies in the meaning of "indiferente". Unfortunately, once again RAE's dictionary is not thorough enough. In the Free Dictionary, we find two possible acceptations for this adjective which are related to the case at issue:

3. Que no despierta deseo, afecto o interés en otra persona Él y su compañero me son indiferentes.
4. Que no se emociona, apasiona o conmueve Es indiferente a la miseria.

(3) would apply to the case of Juana not arousing my interest, and (4) to the case of "I" feeling indifference or apathy toward Juana.