Lieutenant General Ben Hodges, commander of the US Army in Europe, said Britain’s position as a key ally and a leading member of Nato would be at risk if its armed forces “got any smaller”.
The strong warning comes as the Army, Navy and RAF have all been ordered to make cuts by the Ministry of Defence (MoD), to save £20 billion in efficiency savings.
So far, the British Army has already been slashed from 120,000 to just 82,000 regular troops. Lt-Gen Hodges said:
“I don’t see how you could maintain those global commitments if you got any smaller.”
It is one of the biggest challenges facing Gavin Williamson, who replaced Sir Michael Fallon as defence secretary following his resignation last week.
Mr Williamson is attending his first Nato Defence Ministers meeting in Brussels where he is expected to meet the US Defence Secretary, James Mattis, for the first time.
Responding to the reports that Britain’s amphibious capabilities could be sold to raise funds, Lt-Gen Hodges said:
“I’d hate to lose that particular capability… Whenever you take something off the table unilaterally then you’ve just made the job a little simpler for a potential adversary.”
General Hodges has consistently urged Nato allies to do more to meet the threat posed by Russia.
During his three years as Commander of the US Army in Europe he has overseen an increased American military presence and a higher tempo of training and exercises.
Most Nato countries have reversed recent defence cuts.