The latest figures showed the Army was more than 7,000 troops short of the government's target of 82,000.
In July there were 74,440 full-time and fully-trained troops, down from 76,880 last year, Presstv Reported.
There were smaller declines for the RAF and navy but they also failed to meet their target strength.
The RAF total stood at 29,930 of the required 31,840, while the Royal Navy and Royal Marines dropped to 29,090 of the required 30,600.
Observers are highlighting the UK’s growing reliance on the United States as the dominant military power, often taking orders from Washington in cases of conflict, such as the recent maritime piracy of an Iranian tanker off the shores of Gibraltar.
This is while Britain’s decision to join the so-called US “coalition” to supposedly protect shipping lanes in the Persian Gulf has not come as a surprise to observers.
The UK initially announced its intention to form a “coalition” with European countries, but was unable to secure even one fully paid up partner.
In view of Britain’s diminished naval capacity, the royal navy risks looking inept and clumsy by over-stretching itself in the Persian Gulf.
PM Boris Johnson’s subservience to the US, as other nations keep their distance, is predicted to further isolate Britain from the world stage.