British Prime Minister Boris Johnson has praised the United States as an “invaluable ally”, recalling the Trump administration’s support for the UK after the Salisbury poisonings.

Speaking at a press conference after a NATO plenary session and working lunch, Prime Minister Johnson said: “The United States is the guarantor and massive contributor of NATO. It has been, for 70 years, a pillar of stability for our collective security.”

Demonstrating the U.S.’s willingness “to stand shoulder-to-shoulder with us”, he recalled the poisonings of former Russian military officer and British double agent Sergei Skripal and his daughter Yulia in Salisbury, England, in March 2018 with a Novichok nerve agent. Then-Prime Minister Theresa May said it was “highly likely” that Russia was responsible.

While nations ejected Russian diplomats — the UK expelling 23 undeclared intelligence officers — Mr Johnson said the United States “expelled 60, and that was a fantastic testament to the transatlantic alliance”.

“America stood should-to-shoulder with us then and has done for decades and is an invaluable ally and continues to be so,” Johnson added.

Prime Minister Johnson made the declaration of Anglo-American friendship after outlining the progress made between NATO members to increase commitment to the defence union, which was made amidst an atmosphere of renewed fellowship.

He reflected that “there was a mood of very great solidarity and determination and a willingness to push NATO forward. Not just in the next few years, but in the next 70 years — a real belief in the longstanding value of this alliance.”

Johnson said that NATO has been successful in the campaign to increase alliance-wide defence spending since the Cardiff Summit in 2014 when members agreed to increase nations’ expenditures to a minimum of two per cent of GDP within a decade.

He said that there had been a “substantial increase” in spending from European members of $130 billion, adding that will rise by $400 billion by 2024.

“At this meeting here today, country after country pledged or gave an account of how they were going to meet the pledge of two per cent,” Mr Johnson said, before outlining how the UK leads in the European contribution to the NATO readiness initiative.

“We are contributing one armed brigade, two squadrons of fast jets, [and] six major warships including the two aircraft carriers.” Several other delegations also said they were going to step up in the readiness initiative.

U.S. President Donald Trump later tweeted that “great progress has been made by NATO over the last three years… NATO will be richer and stronger than ever before.”