The 'utterly dire' state of the Royal Navy fleet can be revealed today, with not one of its six attack submarines at sea.
Only nine out of 25 warships and attack – as opposed to nuclear – submarines are active or deployed.
The rest of the fleet has racked up a staggering 30 years of missed days at sea as vessels are either broken down, being modified or undergoing trials.
The shocking figures, confirmed by Navy sources, emerged as fears intensify over the future of the Armed Forces.
Despite the threat posed by Russia, instability in the Middle East and the rise of China, the new Government is making defence cuts.
As the Mail revealed as part of its Don't Leave Britain Defenceless campaign, training budgets are being slashed so a £400 million pay rise for troops can come from existing budgets.
Retired Rear Admiral Chris Parry said last night: 'This situation is utterly dire – we haven't got enough ships to protect our aircraft carriers and we haven't got any attack submarines to protect our nuclear deterrent.'
It is understood that shortages of engineers and dry-dock facilities are exacerbating the situation.
The worst offenders in the naval fleet are assault ship HMS Bulwark and destroyer HMS Daring – which have both been inactive for more than seven years.
The submarine HMS Ambush has apparently been idle for 765 days since taking part in Nato exercises in the Arctic in 2022.
Most alarmingly, the shortage of attack submarines has apparently led to US submarines being called on to protect the UK's 'bomber' submarines.
The four 'bombers', at least one of which has to be at sea, carry this country's nuclear deterrent.
No details can be revealed about this quartet – Vanguard, Vengeance, Victorious and Vigilant – because of their top security classification.
While previously the Vanguard-class submarines may have spent three months at sea at a time, recently this has been extended to six months.
In September last year, one returned to port after 195 days – with its hull covered in barnacles.
Rear Admiral Perry added: 'The world is too big for us to rely on the Americans: the US has other roles.
'There is a basic lack of honesty here. The Navy will say it is fulfilling its obligations when it isn't.
'We're supposed to be a maritime nation, and Europe's leading maritime nation.
'Most of the ships and submarines are ridiculously old. They're still in service because we're taking too long to build replacements.
'The Chinese navy are producing ships in as little as a year and a-half, we are taking closer to seven years.'
In recent weeks, the Mail has revealed how training budgets have been reduced, overseas exercises are being scaled back and units have been told to expend less ammunition.
Defence Secretary John Healey said his department would 'do its bit' to meet Treasury-imposed savings targets.
Desperate officials even told the Chelsea Pensioners to expect their annual £13 million 'grant in aid' to be axed – a move which could have caused the closure of the Royal Chelsea Hospital.
The hospital confirmed discussions had taken place with the Ministry of Defence over funding, but the move was reversed.
Following the launch of this newspaper's campaign, the then Tory government set out a timetable for defence spending to hit 2.5 per cent of gross domestic product by 2030. Labour has refused to match that commitment.
The MoD is also facing a £16.9 billion 'black hole' in its spending plans over the next decade, according to the National Audit Office.
The open-source data about the Navy's active vessels first appeared on the 'Britsky' defence account on X.
The Navy said: 'These tables are not derived from any official source. All Royal Navy ships rotate through planned operating cycles.
'We continue to meet our operational requirements.'
