WASHINGTON - The Pentagon approved the Navy's decision to lift the ban on women serving in submarines.

In a letter to congressmen, required by law, Defense Secretary Robert Gates expressed the State Department's support of the decision, saying the Navy would institute it in a "phased approach."

"This is fundamentally a Navy initiative, which they recently briefed to the secretary of defense," Pentagon press secretary Georff Morrell told reporters. [He] supports it and he notified Congress of the Navy's plans," he said.

Congress has 30 days to respond. If legislators affirm the change, the Navy will be able to begin deploying women to submarine crews when the ban expires at the end of April.

Women make up approximately 15 percent of the 336,000 people serving in the Navy. Since 1993, they have been able to serve on most surface ships, but have been banned from submarines because of the close quarters.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, expressed his support for the initiative in congressional testimony last fall.

During his tenure as Navy chief of operations, Mullen oversaw research on women serving in submarines.