As the guys above said.
If you look at it you will clearly make out that the Tanto blades were designed to be used as a slashing and stabbing weapon. The point or tip is designed in such a way that it stays "thick" in the middle of the blade, the spine and all the way to the tip and is strong enough for stabbing through tough things like body armour.
Now the fact is that probably when you and all of us refer to a tanto we refer mainly to the Americanized version of the tanto (like the Recon Tanto) which is a bit unlike a classic Japanese tanto and looks like:
Japanese tantos did not really have the angled tip like the american tantos. The original term did not refer as much to the blade shape or the tip as the type of knife. The Japanese tango was designed primarily for stabbing and the american tanto is a mixture of aggressive looks

, tip strength etc.
This is what Benchmade has to say "TANTO: Most tantos seen on the American cutlery market are Americanized formats. Like the Japanese tanto, the Americanized tanto has a high point in-line with the pivot. A flat grind is applied to the point, leaving it very thick and extraordinarily strong. This thick area helps absorb the impact from piercing, as the tanto was originally designed for armor piercing. The front edge meets the bottom edge at an obtuse angle rather than curving to meet it as seen in the Japanese tanto. The only negative aspect of the tanto blade shape is the cutting surface area is sacrificed to gain tip strength."
Personally speaking I am not a big fan of the Americanized tanto. I prefer the drop points or similar styles. These have more utility and are functional. A tanto point blade you can use for leverage to open a box

. These blades also lack the "belly"or the curves and to me this is a drawback when it comes to slashing.
I don't know if this answers your query.
So what is it that makes the tanto geomety so suitable for combat/knife fighting purposes. Are these knives standard issue to any infantry/spec ops units around the world ?
Again it depends on the style of tanto you are referring to. The fact is that a Bowie or a Ka bar is as good as a combat knife as any Tanto + they offer more utility and are graceful.
I do not know or think that the tantos are standard issue to any special ops group but a lot of double sided daggers and drop points are.