New York (CNN Business) Tariffs and the trade war with China are the biggest near-term financial problems facing the United States. But one market expert thinks the United States needs to focus on a longer-term issue if it wants to remain on top of the world's economic heap: immigration.

David Kelly, chief global strategist with JPMorgan Funds, argued in his most recent weekly report that America could soon face a big labor shortage as more baby boomers reach retirement age. There aren't enough younger people currently to replace them.

He said that many people, including members of the Trump administration, are focusing too much on trying to find ways to stimulate more demand via tax cuts and calls for the Federal Reserve to lower interest rates.

But Kelly thinks the biggest looming problem for the United States is about the supply of people in America that are of working age and able to keep spending.

Unless America adds more younger people to the labor force, Kelly argues that any tax cuts or other stimulus would be "more pointless than a fast car in a big city."