Clinton, the Democratic front-runner for president, said she was "shocked by the time-worn tactic of once again impugning the patriotism of any of us who raise serious questions" about the Iraq war.
Sen. John Kerry, the 2004 Democratic candidate for president, joined Clinton in a conference call with reporters to discuss new legislation aimed at forcing the Pentagon to answer congressional questions about plans for the eventual departure of U.S. troops from Iraq.
Talk of such legislation came after a top Defense Department official wrote to Clinton saying such questions boost enemy propaganda.
Clinton called that argument offensive, and argued it was more evidence that smart military planning is being subverted by misguided White House political strategies.
Clinton first raised the issue in May, pointing out that whenever troops leave, it will be no simple task to transport the people, equipment and vehicles out of Iraq, possibly through hostile territory.
The response penned by Eric Edelman was sharp.
"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," Edelman wrote.
His tough language in a letter obtained Thursday by The Associated Press was surprising in part because it came in correspondence with a member of the Senate Armed Services Committee, which has oversight of the Pentagon.
Clinton has replied with her own letter to Edelman's boss, Defense Secretary Robert Gates, asking if he agreed with Edelman's charge.
The New York senator wrote Edelman had ducked her questions and "instead made spurious arguments to avoid addressing contingency planning."
"Undersecretary Edelman has his priorities backward," Clinton wrote, calling his claim "outrageous and dangerous."
She repeated her request for a briefing — classified if necessary — on the issue of end-of-war planning.
The senator's spokesman Philippe Reines said: "We sent a serious letter to the Secretary of Defense, and unacceptably got a political response back."
As she runs for president, Clinton has ratcheted up her criticism of the Bush administration's war effort, answering critics of her 2002 vote to authorize the Iraq invasion by saying she would end the war if elected president.
Edelman is a former aide to Vice President Dick Cheney, and a public feud between him and Clinton may win her points among anti-war voters and liberal Democrats, a critical constituency in primary voting.
Among her top Democratic rivals, Sen. Barack Obama of Illinois has argued that he opposed the war from the start when he was serving in the Illinois legislature. John Edwards, the former North Carolina senator, has disavowed his 2002 vote giving President Bush the authority to oust Saddam Hussein's regime.
Her response to Edelman also suggests Democrats are still smarting from what they claim were rough Republican tactics during the 2004 presidential race. Democrats also directed some of their ire at then-nominee Kerry, contending that he did not respond quickly or forcefully enough to broadsides such as the unsubstantiated allegations from the Swift Boat Veterans for Truth.
If she ultimately wins the White House, Clinton may find herself overseeing a troop withdrawal, but others have also raised the issue, including Republican Sen. Richard Lugar of Indiana.
Edelman's letter does indicate the Pentagon might be planning how to withdraw, saying: "We are always evaluating and planning for possible contingencies. As you know, it is long-standing departmental policy that operational plans, including contingency plans, are not released outside of the department."