To the point: Deploying to attack is different than deploying to defend before an attack.
Imagine if our troops had been in the Aleutions when Japan showed up in 1941 ... we wouldn't have had to retake the islands (while allowing Japan to retain possession of other territories as we geared up for the fight).
Imagine if German troops were already deployed to Iceland when the UK arrived in 1940 ... it would have been a fight, and Germany would have had an advantage.
And, this may not be just about land... we are talking control/tracking of sea, air and near space.
The above aren't perfect analogies to the present strategic situation, but they demonstrate the point. And I'm just being devil's advocate here, since I don't have all the facts. I guess we will find out together if any of this is beneficial or stupid.