Former U.S. Defense Secretary Robert Gates has said that cuts to the British military will mean that, "With the fairly substantial reductions in defence spending in Great Britain, what we're finding is that it won't have full spectrum capabilities and the ability to be a full partner as they have been in the past."
Prime Minister David Cameron responded to Gates' comments saying "We are a first-class player in terms of defence and as long as I am Prime Minster that is the way it will stay."
According to the BBC, the British government is planning to cut "30,000 armed forces personnel by 2020, leaving 147,000."
It is worth considering the size of the U.K.'s military given its size.
The U.K. is smaller than Wyoming and has a population roughly one fifth that of the U.S. Despite its small size, the U.K. is the fourth largest military spender in the world.
Of course, the British have fought with the U.S. in a number of military conflicts, most recently in Iraq and Afghanistan. Given how those conflicts worked out, perhaps it would be better for the U.K. not "to be a full partner" with the U.S. in future conflicts.
The British military will be able to defend the U.K. and its territories (which is what it should be used for) even if the planned reductions are accounted for. See graphic on the planned reductions from the BBC below:
Even with a drop in the number of military personnel planned, it is worth remembering that the U.K. is one of the world's few nuclear powers. The U.K.'s military, even post reductions, will be more than capable of deterring attack. That is what British policy makers should be concerned about, not the British military's ability to be a "full partner" in future U.S.-led foreign adventures.