Now that Donald Trump has pillaged $3.6 billion in congressionally approved military construction funds to pay for part of his border wall, the collateral damage is becoming clear.

That big update scheduled for the US Military Academy’s engineering centre? Gone. Five major hurricane-related repair projects on military bases in Puerto Rico? Not happening. Hundreds of millions of dollars to build and refurbish schools for American military children at US facilities at home and overseas? Sorry, kids: Trump wants his wall — the one it turns out Mexico is not paying for.

The pain of Trump’s raid was felt even by Republicans, although the Pentagon’s building projects in their districts and states were ransacked to a somewhat lesser degree than those in Democratic areas, according to an analysis by Politico. Most took it stoically, while suggesting that Congress should now step up to replenish what the President had robbed.

Trump has justified his raid on military funds by citing what he calls a national emergency along the southern border — namely, illegal crossings by migrants from Central America. As it happens, those crossings have fallen by more than half since they spiked in May, as measured by Border Patrol apprehensions.

Still, if money appropriated by the legislative branch can be snatched away so cavalierly by the executive, what is to stop a Democratic president from invoking national security to redirect funds — from military bases or even, say, farm subsidies — to promote gun safety, or for some other favoured policy?

The projects sacked by Trump come from military installations in nearly half the states, plus three US territories, as well as bases and facilities on the territory of America’s European allies.

Puerto Rico, for which the President expresses open contempt, was a special target; plans at facilities there will lose more than $400 million.

Projects at bases in Guam, which North Korean president Kim Jong Un explicitly threatened with nuclear attack, were whacked by $257 million. More than $700 million was snatched from sites in Europe, mainly for projects designed to protect the Continent from Russian aggression.

Pete Buttigieg, the mayor in South Bend, Indiana, and a Democratic primary hopeful, made the point that one project now mothballed by Trump’s move, a cybersecurity centre in Virginia, seemed a more contemporary national security priority than what he regards as Trump’s 17th-century border barrier.

“The biggest threats to this country aren’t things that are stopped by walls,” Buttigieg said.

That’s accurate.