The US deficit running to billions of dollars have so far been funded by trade surplus countries like China and Japan and other OPEC and Asian countries. With the current economic crisis striking at the heart of every country, most of these countries are seeing their trade surpluses vanishing and are therefore unlikely to continue investing in US.
This only means that US will have to find some other way of funding its deficit which could be very costly and long term damaging for their economy. Let us wait and see how the situation evolves over the coming months.