Boris Johnson is to urge Nato leaders to redouble their commitment to collective security as the world emerges from the coronavirus pandemic.
After hosting the G7 in Cornwall, the Prime Minister will travel to Brussels on Monday for a summit of the Western alliance.
He is expected to use the meeting to highlight the way the Covid crisis was exacerbated by security threats – including cyber attacks on the healthcare systems of some alliance members.
He will also back the modernisation programme instituted by Nato Secretary-General Jens Stoltenberg, saying the alliance must be prepared to face down the challenges of the future.
“Nato is not just important to the UK’s security, it is our security,” Mr Johnson said in a statement ahead of the summit.
“Nato owes it to the billion people we keep safe every day to continually adapt and evolve to meet new challenges and face down emerging threats.
“As we recover from the global devastation wreaked by the coronavirus pandemic we need to do so with secure foundations.
“The peace and stability brought by Nato has underpinned global prosperity for over 70 years, and I have every confidence it will continue to do so now.”
As leaders prepared to travel to Brussels, Mr Stoltenberg said relations with Russia are at the “lowest point” since the end of the Cold War.
He said there is a “pattern of Russian behaviour” from cyber attacks through to the willingness to use military force against neighbours such as Ukraine and Georgia.
“We see attempts to meddle in our political democratic processes, to undermine the trust in our institutions and efforts to divide us. We have to take that very seriously,” he told Times Radio.
“We need to strengthen our cyber defences, we need to exchange intelligence, we need to be vigilant and aware of all these different tools of aggressive actions, military and non-military.”
Meanwhile, Defence Secretary Ben Wallace suggested former prime minister Theresa May would be an “excellent” candidate to succeed Mr Stoltenberg when he steps down next year.
“Theresa May was a fantastic prime minister in really tough times,” he told Italian political magazine Formiche.
“I worked with her as the security minister. She would be an excellent candidate.”