US total private construction spending on manufacturing remains down more than 20% year over year despite the ongoing AI capital expenditure boom, according to the source post. The post argues that spending on productive capacity could have been higher and raises the prospect of further weakness if AI-related capex declines. The source does not provide additional figures beyond the year-over-year drop or specify the underlying dataset in the text provided. The commentary on Iran spending and a potential AI capex bust reflects the author's opinion.