No threshold for the link --- no one knows when borrowing is TOO MUCH --- U.S. can continue to borrow and increase spending

(David, “How worried should you be about the federal deficit and debt?,” pg online @ https://www.brookings.edu/articles/how-worried-should-you-be-about-the-federal-deficit-and-debt/ //um-ef)

Is debt at that level a problem? For now, it isn’t. The U.S. government borrows trillions of dollars a year at very low interest rates on global financial markets, and there doesn’t appear to be much private sector borrowing that is crowded out by U.S. Treasury borrowing right now. Indeed, the fact that global interest rates remain very low while governments around the world are borrowing heavily to fight the COVID-19 recession suggests that there is still a lot of savings around the world, more than is needed to finance private investment. No one really knows at what level a government’s debt begins to hurt an economy; there’s a heated debate among economists on that question. If interest rates remain low, as currently anticipated, the government can handle a much heavier debt load than was once thought possible. And the recent increase in borrowing—while enormous—is a temporary increase intended to combat an emergency; it changes the level of the debt, but not its long-run trajectory.