The world is entering a "dangerous new age of proliferation", with threats from genetic weapons, lasers and nuclear warheads, the UK's national security adviser has said.
Sir Stephen Lovegrove raised the spectre of a "collapse into uncontrolled conflict" unless methods are devised to deter hostilities and impose controls over the spread of ever-more deadly weapons that have become increasingly easy to acquire.
In a rare and very frank public speech during a visit to the United States, he warned how mechanisms developed during the Cold War by and between Western allies and the then Soviet Union to prevent either side from triggering a nuclear exchange were no longer sufficient.
He highlighted concerns about China's nuclear weapons programme in particular.
"We should be honest - strategic stability is at risk," Sir Stephen said at the Centre for Strategic and International Studies in Washington.
He described Russia's war in Ukraine as a manifestation of a much broader contest that is challenging the international order.
Analysts see this as a battle of values between the world's liberal democracies, led by Western allies, and authoritarian states such as China and Russia.
"As this contest unfolds, we are entering a dangerous new age of proliferation, in which technological change is increasing the damage potential of many weapons, and those weapons are more widely available," the top British security official said.
"We need to start thinking about the new security order."
Dangerous weapons are becoming easier to acquire
This involved an "urgent" look at two elements that have helped to keep global peace since the end of the Second World War.
First involved the ability of Western allies to deter attacks by their enemies.
The second was a network of international agreements to control the spread of weapons, including nuclear, biological and chemical arms.
"The question is how we reset strategic stability for the new era - finding a balance amongst unprecedented complexity so there can be no collapse into uncontrolled conflict," Sir Stephen said.
"The circle can only be squared if we renew both deterrence and arms control, taking a more expansive and integrated approach to both."
Setting out the challenge, Sir Stephen said there is a growing set of weapons that is becoming increasingly easy to acquire - and not just by national governments.
This includes cyber weapons, drones and chemical and biological threats.
They may not be enough to trigger a war but could cause instability with unpredictable consequences.
There is then an array of emerging technologies only developed by the most powerful states, which could "upset the strategic balance", the national security adviser said.
Cyber is in this category as well alongside "space-based systems, 'genetic weapons', nuclear-powered cruise missiles, directed energy weapons and hypersonic glide vehicles", Sir Stephen said.
So-called genetic weapons sound like something out of a science fiction novel but a member of the US Congress claimed during a security forum in Aspen, Colorado, last week that bio-weapons are being developed that use a target's DNA to go after only that person.
Concerns over China's nuclear modernisation
The British national security adviser also warned about "novel nuclear technologies", singling out China.
"We have clear concerns about China's nuclear modernisation programme that will increase both the number and types of nuclear weapon systems in its arsenal," he said.
Sir Stephen said tackling the threat posed by the proliferation of new weapons was a "daunting prospect" and while securing new international agreements with major powers was a long-term goal "there is no immediate prospect" of that happening.
As a result, the focus should be on reducing the risk of any escalation, he said.
This would involve things like establishing norms of behaviour and working to find common ground and mutual benefits between all parties using the particular weapons.
The UK, the US and other Western allies should also seek to engage with as wide a group of countries across the globe as possible.
Lines of communication should also be kept open with adversaries.
"We want 'jaw-jaw not war-war'," Sir Stephen said, drawing on a Winston Churchill quote.
He was speaking ahead of a review next month of a United Nations treaty aimed at curbing the proliferation of nuclear weapons.