China is trying to limit the scope of Australia's longstanding security alliance with the United States after last week's revelations about B1 bombers being mooted for Darwin by declaring that defence co-operation with Washington should not "harm the interests" of Beijing.

Canberra and Washington have both denied since there are any plans for northern Australia to host bombers or surveillance aircraft, insisting Assistant Defence Secretary David Shear "mispoke" when he said it was part of a strategy to counter Beijing's aggression in the South China Sea.