Why a Neutron Bomb explosion in Yemen is really serious

The primary problem is precedent. Once one nation uses something nuclear then other nations are bound to do the same. For example, the U.S. and Russia and other nations use nuclear material on anti-tank rounds in order for them to melt through to the living compartment on tanks. So, whenever these "Nuclear tipped or coated rounds" come into the battle in a sense you have introduced (nuclear weapons) onto a battlefield. It is the same kind of thing with chemical weapons. Once one side uses chemical weapons other sides think it's okay too.

So, the real problem with  one or more neutron bombs going off in Yemen is that likely there will be more unless there is a real outcry from the world now.

ON the other hand neutron bombs are pretty expensive and hard to make and somewhat rare. So maybe this will limit their use somewhat too.