His intervention comes amid reports that Theresa May and Chancellor Philip Hammond have clashed with Defence Secretary Gavin Williamson over the level of military capability the UK needs to maintain.
After the Prime Minister's promise of £20 billion-a-year extra for the NHS, allies of Mr Williamson on the Tory backbenches are reportedly threatening a revolt if there is no additional funding for defence in the Budget in the autumn.
The US-UK Defence Gap
The committee said that US Defense Secretary James Mattis had estimated that the UK benefited to the tune of £3 billion-a-year from its defence relationship with the US.
"This implies that both the UK armed forces and HM Treasury benefit from our close relationship with the US."
"However, that will continue to be true only while the UK military retains both the capacity and capability to maintain interoperability with the US military and to relieve US burdens.
"For this to be the case the UK armed forces must be funded appropriately."
Mr Trump called the current arrangement a rip-off and warned that "change is coming".
....And add to that the fact that the U.S. pays close to the entire cost of NATO-protecting many of these same countries that rip us off on Trade (they pay only a fraction of the cost-and laugh!). The European Union had a $151 Billion Surplus-should pay much more for Military!
....Germany pays 1% (slowly) of GDP towards NATO, while we pay 4% of a MUCH larger GDP. Does anybody believe that makes sense? We protect Europe (which is good) at great financial loss, and then get unfairly clobbered on Trade. Change is coming!