From this wiki page we can clearly see that US national debt is growing steadily after 2010 and now it's larger than US GDP already (at the end of 2019).
Still it's commonly believed the debt is maintainable. At least, neither the Obama administration nor the Trump administration care to spend (enough) effort to eliminate the debt.
I wonder, at what point (or at what debt/GDP ratio) would the US government truly lose control over the debt?