Not long before World War I, HMS Dreadnought, a battleship that made all existing vessels obsolete, was launched at Portsmouth in the presence of the King-Emperor Edward VII. Fire-breathing patriots soon took up the cry, ¡°We want eight and we won¡¯t wait.¡±

Winston Churchill, then a young home secretary in a government committed to spending more on welfare, wryly noted of the popular clamor for a naval race with Germany: ¡°The Admiralty had demanded six ships; the economists offered four; and we finally compromised on eight.¡±

British debates about defense spending follow a familiar trajectory, although this time it¡¯s politicians, rather than civilians, insisting that more should be spent on firepower. A military revolution in warfare is under way, too. Drones, off-the-shelf technology far cheaper than dreadnoughts, are being deployed to lethal effect on the battlefields of Ukraine and further afield ¡ª the daring ¡°Spider Web¡± raid recently destroyed as much as a third of Russia¡¯s strategic bombing force based thousands of miles away from Europe.

But the U.K. needs to replace expensive military hardware too and make good shortages of munitions. Economists fear the government can¡¯t afford the outlay without large tax increases. Who will prevail?

In a speech prior to the publication of his government¡¯s Strategic Defence Review (SDR) recently, Prime Minister Keir Starmer sounded eerily reminiscent of an old-fashioned jingoist, circa 1914. Britain, he said, faces a threat ¡°more serious, more immediate and more unpredictable than at any time since the Cold War.¡± The U.K. needs to move to ¡°war-fighting readiness.¡±

Alas, reality and rhetoric don¡¯t match. U.K. defense spending is planned to rise to only 2.5% of gross domestic product by 2027, with a notional ambition to reach 3% by the mid-2030s. In the 1980s, at the end of the Cold War, it stood at almost 4%. When the dogged Defense Secretary John Healey attempted to impose a fixed timeline for a bigger military budget, he was immediately slapped down by the Treasury.

Within days, however, the NATO trumped Starmer. The Western Alliance has reached near consensus on a 5% commitment, with 3.5% going directly on the armed services and a further 1.5% on related spending. On June 5, U.S. Secretary of Defense Pete Hegseth, ordered Starmer to saddle up, saying ¡°it is important that the U.K. gets there.¡± On June 3, German Defense Secretary Boris Pistorius talked of raising expenditure by annual increments to reach 5% of GDP, aimed at creating the strongest conventional army in Europe.

At home, the popular hue and cry is not for an arms race with Russia, which remains a niche preoccupation at Westminster and in security circles, but for reversing cuts to pensioners¡¯ winter-fuel allowances. Labour¡¯s...