Nato decisions are only taken by consensus. Sánchez’s opt-out rests on a change in the text from “we” to “allies” in the sentence referring to the pledge to spend 5 per cent of GDP on defence by 2035, said two officials involved in the negotiations.

NATO members agreed to a big increase in their defence spending target to 5% of gross domestic product, as demanded by President Donald Trump, but Spain said it did not need to comply just days before a summit in The Hague meant to be a show of unity.