WASHINGTON — The acrimony between Senator Clinton and the Defense Department over the Iraq war is escalating after a top Pentagon official scolded the presidential hopeful for reinforcing “enemy propaganda” with talk of a withdrawal of American troops. In a letter released yesterday by Mrs. Clinton’s Senate office, the undersecretary of defense for policy, Eric Edelman, rejected her request to see the Pentagon’s contingency plans for pulling out American forces from Iraq if Congress succeeds in its push to demand a military withdrawal.

Mr. Edelman also used strong words to caution the New York senator against continuing to stir discussion of an American exit from the war, saying such talk had had harmful repercussions in previous military efforts, including one in Somalia during her husband’s administration.

“Premature and public discussion of the withdrawal of U.S. forces from Iraq reinforces enemy propaganda that the United States will abandon its allies in Iraq, much as we are perceived to have done in Vietnam, Lebanon, and Somalia,” Mr. Edelman wrote. “Such talk understandably unnerves the very same Iraqi allies we are asking to assume enormous personal risks in order to achieve compromises on national reconciliation, amending the Iraqi constitution, and other contentious issues.”

He added that fear of a fast American departure “exacerbates sectarian trends” in Iraqi politics, where officials look for quick tactical advantages rather than long-term accords.

Mr. Edelman was responding to a letter Mrs. Clinton sent on May 23 to Secretary of Defense Gates and the chairman of the Joint Chiefs of Staff, General Peter Pace. Mrs. Clinton sits on the Senate Armed Services Committee.

Mr. Edelman’s response, dated July 16, was first reported yesterday afternoon by the Associated Press.

Mrs. Clinton showed no signs of backing down yesterday. Her Senate spokesman, Philippe Reines, called the response “at once outrageous and dangerous,” and he said the administration “must immediately provide a redeployment plan that keeps our brave men and women safe as they leave Iraq — not a political plan to attack those who question them after years of miscalculations and misjudgments.”

Echoing the kind of heated rhetoric that Mrs. Clinton employs on the campaign trail, Mr. Reines said that “redeploying out of Iraq with the same combination of arrogance and incompetence with which the Bush administration deployed our young men and women into Iraq is completely unacceptable.”

He said Mrs. Clinton sent a letter in response to Mr. Gates, which was not released publicly. As Mrs. Clinton seeks the Democratic nomination for president, she has stepped up her criticism of the Bush administration’s Iraq policy, embracing a timetable for withdrawal of troops and pledging to end the war if she makes it to the White House. In May, she joined her chief rival, Senator Obama of Illinois, in voting against an emergency funding bill after Democrats stripped a withdrawal requirement in the face of a presidential veto threat. The shift is seen as an effort to mollify the party’s fervently antiwar base, which has long called for an immediate American exit from Iraq.

At the same time, Mrs. Clinton has sought to burnish her military credentials as she vies for the job of commander in chief. In the Democratic presidential debates, she has consistently appeared the most hawkish of the leading candidates, vowing to retaliate militarily against terrorist attacks and affirming her commitment to the war on terror.

The letter she sent to Mr. Gates and General Pace seemed to illustrate that dual strategy, as she urged a withdrawal while remaining cognizant of the potential danger to American soldiers. “The seeds of many problems that continue to plague our troops and mission in Iraq were planted in the failure to adequately plan for the conflict and properly equip our men and women in uniform,” she wrote then. “Congress must be sure that we are prepared to withdraw our forces without any unnecessary danger.”

Mr. Edelman wrote that “as with other plans, we are always evaluating and planning for possible contingencies,” but he cited long-standing policy that such plans are not released outside the Defense Department.

The exchange between Mrs. Clinton and the Pentagon comes as American military officials in Iraq are urging Congress to give President Bush’s troop surge more time to secure Baghdad and other unstable regions in the country.

Mr. Edelman made a similar case to Mrs. Clinton in his letter, writing that “because these operations will continue for many months, it is too early to assess whether this new strategy will be successful, and it is premature to say with certainty whether and how a future phased withdrawal would be conducted.” He reiterated his view that a “rapid” pullout would undermine tactical successes that have been achieved.

Despite the under secretary’s strong language, a Pentagon spokeswoman characterized the letter as part of routine correspondence between defense officials and Congress.