In a move that has rattled gilt markets and sent the pound sliding, President Donald Trump has formally requested billions of dollars from Congress to fund military operations against Iran. The request, made during a live address, comes as the UK government warns that any escalation could trigger a broader regional conflict with devastating economic consequences.
For those of us who have watched the bond markets for decades, this is a familiar pattern. War spending means more debt, more issuance, and ultimately, higher yields. The 10-year gilt yield, which had been hovering around 4.5%, shot up 12 basis points within minutes of the announcement. Investors are pricing in risk, and they are not buying the government’s promise of fiscal discipline.
The UK's warning is not just diplomatic noise. The Foreign Office has issued a statement cautioning that a full-scale conflict would destabilise oil markets, disrupt supply chains, and trigger capital flight from emerging markets. The Treasury will be watching the oil price closely: a sustained spike above $100 a barrel would hammer UK consumers and blow a hole in the Chancellor's fiscal plans.
Let us be clear about the numbers. Trump is asking for an initial $5 billion, but defence analysts expect that figure to balloon. The last time the US engaged in a prolonged Middle Eastern campaign, the total cost exceeded $2 trillion. Even a fraction of that, funded by debt, would put upward pressure on global interest rates. The Federal Reserve will be forced to choose between fighting inflation and financing war.
Market volatility is already evident. The S&P 500 futures dropped 1.8% in after-hours trading. Safe-haven assets like gold and the Swiss franc are surging. The dollar, paradoxically, is strengthening on fear. This is capital flight in action: investors are fleeing equities and bonds for cash and gold.
The UK's position is precarious. We rely on imported energy and have a current account deficit that requires constant foreign capital inflows. Any disruption to confidence could see sterling tumble. The Bank of England will be on high alert, but its tools are limited. Rate hikes would crush the housing market; keeping rates low would fuel inflation.
Domestically, the timing could not be worse. The UK is already grappling with sticky inflation, a stagnant economy, and a government that has promised lower taxes. War spending by the US will force the Treasury to reconsider its fiscal rules. Defence spending as a percentage of GDP is likely to rise, adding to the fiscal burden.
For investors, the message is clear: reduce exposure to cyclical stocks, increase cash holdings, and consider inflation-linked bonds. The era of easy money is over. We are entering a period of geopolitical risk that will test the resilience of portfolios.
The bottom line is this: war is expensive, and someone has to pay. In this case, it will be taxpayers and bondholders. The UK government's warning is not just about diplomacy; it is about the hard economics of conflict. The markets are already voting with their feet.
