Three Records in Two Days
On Wednesday, 1 October, the US 10-year Treasury yield hit 5.34%, its highest since 2002. The same day, Britain’s 30-year gilt yield broke 6% for the first time since 1998. On Thursday, France presented its 2027 budget, and the gap between French and German 10-year borrowing costs touched 149 basis points, the widest since the euro crisis of 2012.
The French budget shows where this leads. Interest on France’s debt rises to €74.2bn next year, more than the €63.3bn Paris plans to spend on its armed forces. Defence still gets €6.4bn extra. Every other ministry combined gets €1.5bn, and development aid falls. Next week, finance ministers meet in Bangkok for the IMF–World Bank Annual Meetings, the first since this bond sell-off began. The real agenda is who can still afford a foreign policy.
Why Money Got Expensive Again
Stay ahead of the geopolitical week.
MD Briefing delivers expert analysis across five global fronts — the Indo-Pacific, energy, geoeconomics, European security, and the Middle East — every Monday morning. Free.
Three forces are pushing yields up together. The first is the Middle East energy shock: crude is up 36% and wholesale gas 78% since July, reviving inflation just as central banks thought they were done. Markets now expect the European Central Bank to raise its deposit rate from 2.50% to about 2.81% by December, and three of the Bank of England’s nine rate-setters voted to hike in September.
The second is the sheer volume of government borrowing. The US deficit reached $1.97tn in the first 11 months of the fiscal year, and Washington paid $1tn in net interest over that period, more than it spent on defence. The third is a lag that makes the problem worse every month: the average rate on outstanding US debt is still only 3.48%, far below today’s market rates. As old bonds mature and are refinanced, interest bills will keep rising even if yields stop climbing. Modern Diplomacy has examined how this pressure is reshaping Washington’s options. The point here is narrower: interest is now a fixed first charge on every major Western budget, and everything else is decided after it.
Defence Survives. Everything Around It Pays.
Most coverage frames this as guns versus butter, or predicts that bond markets will force governments to abandon their rearmament plans. Neither is happening. France is adding to defence. Germany’s core defence budget reaches €109bn in 2027, as Modern Diplomacy has reported. The White House has asked Congress for a $1.5tn national-defence budget. Defence is protected by the NATO pledge to reach 5% of GDP and by a public that has absorbed the threat from Russia and Iran.
What the bond market is doing is subtler and more consequential. It is setting the price of everything that sits around defence, and foreign policy is mostly made of those things. Interest is the one bill no government can renegotiate, so every rise in yields squeezes the budget lines that have no constituency at home. In France, that means development aid and an employment budget cut by €2.8bn. In the US, it means a defence request that Congress is likely to fund at only 80–90% of the ask, with diplomacy and foreign assistance squeezed first.
Energy relief is the clearest case. EU governments have spent €17.9bn this year cushioning energy prices, more than two-thirds of it on blanket price measures rather than help aimed at poorer households. The European Commission is now urging capitals to target support, and finance ministries will listen because they remember 2022. That autumn, Liz Truss paired an open-ended energy price guarantee with unfunded tax cuts. Gilt yields soared, pension funds came close to collapse, and she was out of office within seven weeks. Every European finance minister knows that story. This winter’s relief will therefore be smaller and narrower than in 2022, even though Europe’s weaker budgets are facing rearmament and an energy crisis at the same time. That is a foreign-policy outcome. Governments that cannot cushion voters from energy costs lose political room to hold sanctions lines and confront the suppliers behind the shock.
Ukraine shows the constraint most clearly. The EU’s €90bn support loan for 2026–27, two-thirds of it for weapons, was not funded from national budgets at all. It is financed by EU borrowing on capital markets, backed by headroom in the EU budget, and meant to be repaid out of Russian reparations. Only 24 member states took part. That structure is itself the bond market’s doing: governments moved Ukraine support off their own balance sheets because their own creditors would not have tolerated it. But the EU borrows in the same market, and when the €90bn runs out at the end of 2027, the next package must be raised at higher rates and backed by governments under pressure, France above all.
The strongest objection is that this is domestic politics dressed up as markets. On this view, France’s spread reflects a minority government and a presidential election in spring 2027, and US yields reflect the Fed and inflation. Governments still choose their priorities; markets merely put a price on them. That is true, and it misses the point. Markets do not vote on foreign policy, but they penalise some choices far more than others. They punish open-ended commitments with no exit date, such as untargeted subsidies or indefinite budget support for an ally at war. They are far more tolerant of hardware spending that looks like investment. The result is a filter applied before any cabinet meets. A government that wants to fund Kyiv beyond 2027, or cap every household’s energy bill, must first persuade its creditors. In practice, that makes bond investors a participant in foreign policy, even though no one elected them.
The filter also shifts power inside Europe. Germany, with debt near 66% of GDP, can borrow heavily for defence. Italy’s spread is now narrower than France’s. Meanwhile France, the EU’s only nuclear power and the loudest advocate of European “strategic autonomy”, has the least fiscal room to lead it. In London, a new prime minister, Andy Burnham, signalled he would seek flexibility within the fiscal rules, and gilt yields jumped. The bond market now sits in on every conversation about who leads Europe’s security.
Three Ways the Squeeze Plays Out
Base case: a slow grind (about 55%). US 10-year yields stay between 5% and 5.5%, and the French–German gap holds between 130 and 160 basis points. Defence plans survive largely intact, while aid, energy relief and non-military foreign spending are trimmed quietly. Ukraine support continues through EU-level instruments rather than national budgets. The key assumption is that the energy shock does not worsen and central banks raise rates once more at most.
Downside: a French accident (about 25%). The National Assembly rejects the budget, or the government falls before the presidential election. The spread pushes through 175–200 basis points, and the ECB faces an awkward question: whether its Transmission Protection Instrument, the tool it created to buy a country’s bonds when spreads widen for reasons unrelated to fundamentals, applies to fiscal stress a government has largely caused itself. If the ECB hesitates, Paris slows the increases in its military planning law, EU joint defence borrowing stalls because France’s guarantee looks weaker, and financing Ukraine beyond 2027 becomes hostage to French politics. Britain’s 28 October budget would be stress-tested in the same weeks.
Upside: the pressure eases (about 20%). Shipping through the Gulf normalises, oil and gas prices fall, and inflation expectations follow. Central banks pause, and long-term yields drop by 50–75 basis points. A third path is political: EU governments agree large-scale joint borrowing for defence, moving the cost of rearmament onto the EU’s stronger balance sheet. That would change the terms of the debate. Today, Berlin’s resistance makes it the least likely of the three.
The Veto Nobody Elected
The bond market is not choosing between guns and butter. It is choosing which kind of foreign policy the West can afford. Hardware survives because it looks like investment. Aid, energy relief and long-term support for allies are squeezed because creditors treat them as open-ended. That is a geopolitical role, played without a seat at any summit.
Watch Wednesday, 14 October, when the IMF publishes its Fiscal Monitor in Bangkok. If it tells advanced economies to consolidate now, defence pledges or not, the Fund will be endorsing the market’s verdict. If it carves defence out of its advice, it will confirm that the squeeze falls on everything else. Western governments can still choose their wars. They can no longer choose what those wars cost.
