Well the tachikomas are a moible tank unit that can think on their own for very heavy combat, like going up against terrorist that will more than likely have an army of followers and and heavy machinery themselves.To the major they are for breeching heavly gaurded areas. in order to obtain her objectives. the tachikomas belong to batu though, i believe.

You are close, Lala.  The Tachikomas are free thinking independent AI tactical tanks. They belong to Section 9, not just Batou, and each member of the section seems to have their own Tachikoma, as was evidenced by Batou giving his natural oil instead of synthetic like the rest. They are supposed to synch with each other after every mission, so that they don't develope individual personalities, but they are often a little sneaky and mischievious, so there are often times where thy don't synch. I think the Major sees herself as a kind of schoolteacher and the Tachikomas are her class. She gives them the orders, and tries to keep them in line, but often secretly smiles about some of their antics or how they come up with a solution to a problem. People fear the strange and unusual. I AM the strange and unusual.

...but what show is this from?  It sounds kinda interesting....^_^; Dewa Mata,Niji-Hana  OTAKU NINJA"If you listen to the world, you'll hear all kinds of false claims about morality. But the gospel offers an unchanging standard of truth."