Psst: The super-secretive National Security Agency is about to build a huge, $1.9 billion data center at Camp Williams, Utah, to help spy on communications worldwide.

The planned work there is so sensitive and classified that Utah's congressional delegation is declining to talk about it, saying it doesn't want to accidentally step over any lines about what can and cannot be disclosed. They referred inquiries to the NSA, which provided only a brief statement confirming the center is coming to Utah.

Utah's National Guard (owner of Camp Williams) was equally mum, with spokesman Lt. Col. Hank McIntire simply divulging that the guard's extent of involvement is to provide the land for the center and be the NSA's "benevolent landlord." He said the project has been in the works for years.

But some interesting details are revealed in unclassified budget-request documents that the NSA sent to Congress.

For example, they say the facility will sit on 120 acres at Camp Williams. They add that the center's mission will be to deliver "responsive, reliable, effective and expert signals-intelligence and information-assurance products and services" to enable "network-warfare operations to gain a decisive information advantage for the nation and our allies under all circumstances."

In other words, it will help with spying on communications.

Many spy novels — especially those by Tom Clancy — have described how the NSA and its satellites and supercomputers can listen for key words or voices in cell-phone, radio, computer and other communications worldwide that may reveal terrorist plans and movements.

President Barack Obama signed into law last week a supplemental war-spending bill that includes the first $169.5 million for construction at the center (after another $207.4 million had been spent on planning it).

Documents say that first batch of money will go to provide utilities to the site and relocate some existing National Guard facilities away from the area. The money will also be used to install initial security items, including perimeter fencing and alarms, an interim visitor control center and a vehicle-inspection center for use during construction.

The money will also fund surveying the site for unexploded ordnance from previous National Guard training and exercises there and take care of remediation as needed.

The NSA has requested another $800 million for the center in 2010 appropriations bills that are now before Congress. That money would fund a first-phase, 30-megawatt data center to include "state-of-the-art high-performance computing devices and associated hardware architecture." Documents project completion of the design work for that first phase by February.