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UK Prime Minister Boris Johnson is set to call for Nato unity, amid growing tensions within the military bloc.
A summit to mark the founding of the 29-member defence alliance 70 years ago begins near London on Tuesday.
The two-day gathering is overshadowed by a bitter row between France and Turkey over the Syrian conflict.
Last month, French President Emmanuel Macron described Nato as “brain dead”, saying alliance members were no longer co-operating on a range of key issues.
US President Donald Trump, who has repeatedly accused Nato’s European members of not paying enough to maintain the bloc’s effectiveness, will be among Nato leaders attending.
What Mr Johnson will say?
Mr Johnson is expected to reiterate the importance of Nato staying united.