Cameron -- a former UK prime minister -- will say that countries need to take more assertive action to protect their interests from emerging threats, including from Russia and Iran.

"We are in a battle of wills. We all must prove our adversaries wrong -- Britain, and our allies and partners around the world," Cameron will say, according to excerpts released by the foreign ministry.

Cameron will use the keynote address at the National Cyber Security Centre in London to call for NATO countries to boost defence spending above a two percent target agreed 10 years ago.

He will call on countries in the 32-member Western defence alliance to "out-compete, out-cooperate and out-innovate" adversaries.

"The upcoming NATO summit must see all allies on track to deliver their pledge made in Wales in 2014 to spend two percent on defence.

"And we then need to move quickly to establish 2.5 per cent as the new benchmark for all NATO Allies," Cameron is due to say.

Last month, UK leader Rishi Sunak announced during a visit to Poland that London would gradually boost defence spending to 2.5 percent of GDP by 2030.

He singled out "an axis of authoritarian states", including Russia, Iran, North Korea and China.

Cameron will argue that the UK needs to invest in old alliances, including the G7 of the world's richest nations and the Five Eyes intelligence-sharing network with the United States, Australia, Canada and New Zealand.

But he will add that Britain also needs to forge new partnerships, like the AUKUS alliance with the US and Australia, post-Brexit.

"We need to adopt a harder edge for a tougher world. If Putin's illegal invasion teaches us anything, it must be that doing too little, too late, only spurs an aggressor on," he will say.

"We need to be tougher and more assertive," Cameron is expected to add.

Cameron, who resigned as prime minister in 2016 after Britons voted to leave the European Union, was plucked from the political wilderness by Sunak to be foreign secretary last November.