Use of "unless"

Quote:

Beacause America has stood by South Korea since the end of the Korean War, South Korea in turn must stand by its ally's side now, they say. This sentiment is admirable and may justify our sending military aid to the United States if it is attacked in the future. However, unless we have now decided to be involved in any and all military conflicts of the United States in all corners of the world, this sentiment cannot justify our involvement in a war against a third party such as Iraq.

I think that the bold part, 'unless we have now decided to be involved' is not correct and instead 'unless we should decide to be involved' is rather correct.
Can you tell me if I'm wrong or right with some explanation?

Thanks.

曼迪

Does this have anything to do with the tense and auxiliary word?
I feel the former version is justified.