Cameron warns failure to supply arms to Ukraine will harm US security

British foreign secretary argues blockage of $61bn aid package in Congress strengthens China and undermines confidence in US

David Cameron has said that the continued US failure to supply arms to Ukraine would undermine its own security, strengthen China and cast doubt on America’s reliability as an ally around the world.

The UK foreign secretary, who attended the G20 meeting in Brazil earlier in the week, admitted that the effort to rally global support for the Ukrainian cause had been “damaged” by the fact that neither the US nor the UK had voted for a UN resolution calling for a ceasefire in Gaza. But he argued the damage had been mitigated by the UK’s clarification of its position.