$127 billion? That's just an ante. A down payment in the biggest, most expensive modernization program in the Army's history: Future Combat Systems, or FCS.

FCS -- the Army's plan to completely overhaul its forces, turning troops into a robot-reliant, network-heavy bunch -- has been slated to cost anywhere from $90 to $127 billion, according to the military.

But on Wednesday, Government Accountability Office eyeshade Paul Francis told the Senate Armed Services Committee said those cost estimates were misleading, at best. The first part of FCS, Francis noted, the one that weighs in at $108 billion, would only cover a third of the Army's troops. How much would it cost to upgrade the rest? Well, given the project's history of delays, switchbacks, poor management, and limp government oversight -- that's anyone's guess, Francis said in his prepared testimony.

Nearly 2 years after program launch and about $4.6 billion invested to date, requirements are not firm and only 1 of over 50 technologies are mature — activities that should have been done before the start of system development and demonstration. If everything goes as planned, the program will attain the level of knowledge in 2008 that it should have had before it started in 2003. But things are not going as planned. Progress in critical areas, such as the network, software, and requirements has been slower than planned. Proceeding with such low levels of knowledge makes it likely that FCS will encounter problems late in development, when they are costly to correct. The relatively immature state of program knowledge at this point provides an insufficient basis for making a good cost estimate.