Donald Trump’s grand vision for a ‘Golden Dome’ missile defence system, intended to protect the United States from intercontinental ballistic missiles, has been costed at a staggering £960bn. For a nation already grappling with a fiscal deficit of 6.4% of GDP, this is not merely a line item; it is a black hole. The price tag alone should give any prudent investor pause. But the deeper concern, for those of us who scrutinise the fine print, lies in what the Military Industrial Complex has left out.

The Government Accountability Office’s preliminary assessment reveals that the system, inspired by Israel’s Iron Dome but scaled to continental proportions, would require at least 30 new interceptor sites, a space-based sensor layer, and battle management software that does not yet exist. The cost overruns, as is customary in these affairs, are likely to be substantial. If history is any guide, the £960bn figure is a starting bid, not a final settlement. The F-35 programme, for instance, started at £120bn and now exceeds £1.4 trillion over its lifetime.

But let us turn to the critical gaps. The report highlights that the system would be ineffective against hypersonic missiles and cruise missiles, which fly at lower altitudes and can evade radar. This is not a minor oversight. America’s adversaries, Russia and China, have invested heavily in these technologies precisely because they bypass traditional missile defences. The Golden Dome, then, is a Maginot Line for the 21st century: a massive sunk cost that leaves the most dangerous threats unaddressed.

Moreover, the fiscal implications are severe. To fund this, the Trump administration would likely need to issue more debt, pushing gilt yields higher and crowding out private investment. The bond market has already signalled discomfort with the trajectory of US fiscal policy. The 10-year Treasury yield, currently at 4.2%, would surely rise if such a commitment were made. Capital flight from US assets is a real risk if investors perceive that the government is prioritising a weapon that does not work over fiscal stability.

In City parlance, this is a ‘value destruction’ strategy. Shareholders in defence contractors like Lockheed Martin and Raytheon may cheer the headline, but the long-term liabilities will erode shareholder value. The opportunity cost is immense. For £960bn, one could fund the entire NHS for five years, or provide a year’s worth of university tuition for every American citizen. Instead, we get a shiny dome with holes.

Central bankers, meanwhile, are watching nervously. The Federal Reserve, which has walked a tightrope between inflation and recession, would face renewed upward pressure on prices if fiscal stimulus from defence spending overheats the economy. The Bank of England, too, would feel the ripple effects as global interest rates adjust.

Yet the political calculus is clear. Trump’s base loves a strong defence. The ‘Golden Dome’ resonates with a public that fears nuclear attack. But the numbers do not add up. The US already spends more on defence than the next ten nations combined. This is not efficiency; it is bloat.

In the end, the market will have its say. Bond vigilantes are patient but ruthless. If the US Treasury issues more debt without a credible plan to close the deficit, the sell-off will be brutal. And the Golden Dome, for all its glitter, cannot protect against that.