The Pentagon is delving into undersea warfare to examine how the U.S. Navy can become technologically superior in shallow-water combat.

The scope of a new undersea warfare study, mandated by the director of Program Analysis & Evaluation, was agreed on in late March, Rear Adm. Paul F. Sullivan said March 31.

"It's looking at improving our undersea-warfare capabilities" and not just submarines, but also off-board, distributed networks of sensors, he said. This marks a shift from the initial impetus of the effort, which some Navy officials feared would focus on the size of the submarine fleet with an eye to reducing it.

The study will include a look at undersea force structure, said Vice Adm. Michael Mullen, deputy chief of naval operations for resources, requirements and assessment. However, the focus will not be on numbers of subs, but on the capability of the undersea force. Mullen is one of the Navy's point men working with the Office of the Secretary of Defense.

"How are we going to operate in an anti-access environment?" Mullen said in an interview. "There's lots of focus on diesel submarines in particular. We need to make coffins out of them. And the way you do that is by lighting up the space so there's no place to hide. And then kill them. So, how do you do that? What technologies do you need? The other very important issue is, 'How can we do this in a time when threats get quieter, stealthier, smaller.' The ability to respond in a very fast way is key."

The study is exploring questions raised by the Office of the Secretary of Defense during the 2004 budget deliberations last fall that ultimately were not answered in time to influence the Defense Department's budget request submitted to Congress in February. Study results are due this summer and have the attention of the Navy's top officer.

Adm. Vernon Clark, chief of naval operations, said he expects the study to recommend a "calculus to maximize our advantage and maximize the disadvantage of the other guy."