Lord George Robertson, a former Labour defence secretary, will use a speech to accuse "non-military experts in the Treasury" of "vandalism".
BBC Verify looks at the size of the UK military after Lord Robertson criticises the government over defence spending.
The US president says Nato "wasn't there when we needed them" during the Iran war.
Germany once terrorised Europe, but now Europe is welcoming a resurgent German military.
Exercise Cobra Warrior sees RAF, German and Polish fighter pilots training at RAF Waddington.
Donald Trump criticised Nato and other US allies, saying he has been told they "don't want to get involved" in the Iran war.
European leaders are hesitant to help Trump secure the Strait of Hormuz, but they know inaction on the Iran war is not really an option.
The government says the nation's defence environment has "significantly changed" since Russia's invasion of Ukraine.
European nations are asking whether traditional alliances can suffice, or whether they should be diversifying
