The West should prepare for all-out war with Russia within the next 20 years, a leading Nato military official has said, as the largest Nato military operation in decades is launched.
Admiral Rob Bauer, a Dutch naval officer and Nato military committee chief, said large numbers of civilians would need to be mobilised and urged governments to put in place systems to manage the process.
Nato, meanwhile, said it will begin Operation Steadfast Defender to test the allies' ability to take on Russia.
About 90,000 Nato troops will next week begin the bloc's largest military exercise since the Cold War.
Admiral Bauer told reporters after a meeting of Nato defence chiefs in Brussels: "We have to realise it's not a given that we are in peace. And that's why we [Nato forces] are preparing for a conflict with Russia.
"But the discussion is much wider. It is also the industrial base and also the people that have to understand they play a role."
As the Russia-Ukraine war bogs down, and with US and European Union funding for Ukraine's conflict-ravaged economy held up by political infighting, Admiral Bauer appealed for a "whole of society approach" that went beyond military planning.
"We need public and private actors to change their mindset for an era in which everything was plannable, foreseeable, controllable and focused on efficiency to an era in which anything can happen at any time," he said as the meeting began.
"An era in which we need to expect the unexpected. In order to be fully effective, also in the future, we need a war-fighting transformation of Nato."
Admiral Bauer praised Sweden for warning its citizens to brace for war ahead of the country formally joined the military alliance.
The speech made by the country's civil defence minister has prompted a surge in the number of people signing up to voluntary defence organisations.
"It starts there," Admiral Bauer said. "The realisation that not everything [can be planned] and not everything is going to be hunkydory in the next 20 years."
On Monday, Defence Secretary Grant Shapps said that Britain would send 20,000 troops to take part in Nato's exercises, with many deployed in Eastern Europe from February to June.
Britain will also send advanced fighter jets and surveillance planes.
Belarus said it would put forward a new military doctrine that for the first time provides for the use of nuclear weapons.
It was not immediately clear how the new approach might be applied to Russian weapons.
US President Joe Biden has claimed that Russia would attack a Nato country if it won the war in Ukraine.Putin last month dismissed his remarks as "complete nonsense", adding that Russia had "no reason" to fight the military alliance.
