Britain and Germany signed a landmark defence treaty on Thursday, further evidence of how European leaders are drawing together to confront a security landscape scrambled by US president Donald Trump’s “America First” foreign policy and Russian president Vladimir Putin’s relentless assault on Ukraine.
The Anglo-German accord, signed by prime minister Keir Starmer and chancellor Friedrich Merz during his visit to London, covers energy, economic co-operation and migration, in addition to defence.
It builds on an agreement signed last October, under which the two agreed to co-operate on mutual defence, with joint military exercises and the development of sophisticated weapons.
The treaty includes a pledge by both countries to regard a threat against one as a threat against the other, declaring that they will “assist one another, including by military means, in case of an armed attack on the other”.
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That echoed language adopted by Britain and France, which pledged last week to more closely co-ordinate nuclear arsenals in responding to threats against European allies.
Germany does not possess nuclear weapons, but it is the third-largest supplier of military hardware to Ukraine after the United States and Britain, according to the Kiel Institute for the World Economy.

Under Mr Merz, Germany has agreed to increase its military spending to 3.5 per cent of gross domestic product by 2029, its most ambitious rearmament since the end of the Cold War.
Britain and Germany have each made strides in recent years in tightening security co-operation and other relations with France, said Mark Leonard, the director of the European Council on Foreign Relations, a research organisation. But the British-German relationship has been slower to evolve.
“The signing of this treaty really is a big step forward,” Mr Leonard said.
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Georgina Wright, a senior fellow at the German Marshall Fund in Paris, said the treaty was, in one respect, an “easy win” for the countries, since Britain and Germany had no institutional framework that formalised their co-operation on defence. “This was about plugging a very clear gap,” she said.
German officials told reporters this week that the agreement, which they refer to as a “friendship contract”, is the latest effort to bring the two countries closer at a time of heightened security concerns, and to bridge divides that had been opened by Britain’s exit from the European Union.
At a time of economic stagnation in Britain and Germany, the friendship agreement includes steps to strengthen commercial ties, from a scientific research partnership to improved rail connections. It also features several measures related to migration.
Those include new co-operation to combat human trafficking and more targeted efforts to make it easier for British and German citizens to visit each other’s countries post-Brexit – like easier passage for British people at German airports, and simpler requirements for German schoolchildren visiting London.
For reasons of diplomatic protocol, Mr Merz’s visit was more modest and businesslike than that of Mr Macron, who was given a horse-drawn carriage ride and a banquet at Windsor Castle.
Unlike Mr Macron, Mr Merz is not a head of state (Germany has a largely ceremonial president). Mr Starmer is the chancellor’s host, while King Charles III invited Mr Macron, reciprocating for his own state visit to France in 2023.
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Still, the lack of pomp and pageantry for Mr Merz says little about the importance of the relationship between him and Mr Starmer. Both are centrist leaders, struggling to govern in polarised political systems.
Both are also relatively new, meaning they could work together for years. Mr Starmer just marked his first anniversary in office; Mr Macron, by contrast, is in the twilight of his presidency, with elections in France scheduled for 2027. – This article originally appeared in The New York Times