The landmark treaty builds on a defense pact the U.K. and Germany, two of the biggest European supporters of Ukraine, signed last year committing to closer co-operation against the growing threat from Russia.

British Prime Minister Keir Starmer suspended several lawmakers on Wednesday as he tried to reassert his authority over his ruling Labour party following a rebellion over welfare reforms. All four voted against the welfare reforms on July 1 after Starmer made his authority-sapping climbdown to avoid a humiliating defeat in parliament.