There is a problem with Afghanistan "falling" to the Taliban. In the days before America arrived in Afghanistan, after Russia had left with its tail between its legs and the Taliban ran free... the Taliban flexed its muscles. One of the ways it did it this was to invade Pakistan at will. It raided and captured Pakistani police stations at will. It did the same with Pakistani military facilities. It attacked and occupied the Pakistani military academy.
Pakistan has nuke weapons. Unlike US controls which require release from the National Command Authority to enable nuclear weapons, Pakistan places the authority to enable nukes along old Soviet lines... giving that ability to local authorities, typically at the two star level.
Now that the Taliban is free to regroup... retrain... thrive and grow... Pakistani nukes are threatened.
That means we are ALL threatened.