Defense Secretary Donald Rumsfeld (search) launched a counteroffensive Tuesday against criticism of how he is conducting the war in Iraq and his seeming insensitivity for not personally signing condolence letters to families of soldiers killed in action.

Rumsfeld frequently visits wounded troops and wrote in an in an op-ed in Tuesday's edition of USA Today about the respect he has for those serving in harm's way.

"The men and women in uniform are putting their lives at risk for our country. Many have paid the ultimate price, and I honor their service and the sacrifice and dedication of their families and loved ones. It is on their behalf that we must do all we can to develop a military designed to meet the challenges of this era," he wrote.

Rumsfeld wrote that he shares the impatience of the soldier who recently asked him about the lack of armor on Humvee (search) vehicles, saying the Defense Department is working to help better equip the nation's military for 21st century threats.

"Our forces must have the equipment they need, and the department is working hard to ensure that they get it," he wrote.

He also explained the unique combat situation U.S. troops face in Iraq.

"The enemies we face today, for the most part, do not have large standing forces or, in some cases, even territory to defend. They know they cannot defeat us on the battlefield, so they choose to fight us in less-conventional ways — ways that play to their strengths, not ours," the secretary wrote.

Rumsfeld wrote that the storming of Baghdad in March 2003 and the defeat of Saddam Hussein's regime with few casualties and little effort "will go down as one of history's great military campaigns." But the enemy already was adapting by using improvised bombs, he wrote.

One of the moves the U.S. military took to respond to the new threats was to boost production of armored Humvees from about 35 per month to about 450 per month. Army experts designed armor kits to retrofit vehicles not originally designed for the added weight, among other things.

Other transformation efforts include buying more Predator aircraft and more precision munitions and canceling expensive Cold War-era Army weapons systems, like the Crusader artillery system and the Comanche helicopter.

"We are in a new century, and we have to make sure that we are organized and equipped for this new century," Rumsfeld wrote. "Our forces have adapted with impressive skill and courage, and they remain the most capable forces in history."

Rumsfeld has been facing a rash of criticism for weeks since he visited troops in Kuwait and was broadsided with a question from a soldier who wanted to know why troops are forced to look in scrap heaps for sheet metal to armor their vehicles. Since then, members on both sides of the aisle on Capitol Hill have questioned his command. Some have demanded accountability of his handling of the war while others have called for his resignation.

"I think it's time for the president to make the decision that someone else should head the Defense Department," outgoing Rep. Martin Frost, D-Texas, told FOX News on Tuesday. "Let's give Rummy his gold watch and move on."

"This is the same Secretary Rumsfeld who failed to provide enough troops necessary to secure Iraq following the fall of Saddam Hussein, who failed to give our troops the body and vehicle armor that could save their lives, and who failed to prevent horrific prisoner abuse in Iraq and elsewhere," House Democratic Leader Nancy Pelosi of California said in a statement on Monday. "At every step, Secretary Rumsfeld has refused to accept any level of responsibility or even admit any mistakes."

A new USA Today/CNN/Gallup poll found that 52 percent of Americans think Rumsfeld should resign, while 41 percent said they approve of the job he's doing.

Despite the criticisms, Rumsfeld is getting support from some other top congressional leaders.

House Majority Leader Tom DeLay, R-Texas, on Monday praised the defense secretary and called on all members of Congress to support President Bush's war Cabinet as elections in Iraq draw near. The election is scheduled for Jan. 30.

Sen. John Kyl, R-Ariz., wrote an op-ed piece in Tuesday's edition of The Wall Street Journal, pointing out how Rumsfeld helped plan the successful ousting of two terrorist regimes in Iraq and Afghanistan and has worked to transform the U.S. military into a quick and nimble force that's better able to deal with today's threats, rather than those of the Cold War era.

"He is tough, no doubt about it," Kyl wrote. "But it takes a tough man to accomplish all this."

Former Texas Republican Rep. Dick Armey said contracts to re-armor military vehicles were submitted years ago.

"That was one of the things he [Rumsfeld] was seriously understanding we need to do even before the Iraq war," the former House Republican leader told FOX News. "He is trying to catch the military up to the events they found themselves in."

One difficult task facing the Pentagon and Rumsfeld, Armey added, was restructuring existing funds within the defense budget for newer, more efficient projects.

"Many members of Congress have hindered his effort so get this reallocation of monies that made sense in the Cold War to new projects that make sense now," Armey said. Frost countered by saying that Congress has voted for all the new projects requested by the administration.

Rumsfeld told FOX News over the weekend that after his four decades of service in Washington, he's used to the "circling the bandwagon" calls and that he doesn't sweat it.

Bush on Monday stood by his man, saying Rumsfeld is the right man for the job and that the job of steering the Pentagon is a difficult one, particularly when the country is engaged not only in Iraq and Afghanistan but a global War on Terror. He also said that Rumsfeld is a compassionate defense chief and cares about each and every man and woman serving their country.

"He's a good, decent man. He's a caring fellow. Sometimes, perhaps his demeanor is rough and gruff, but beneath that rough and gruff, no-nonsense demeanor is a good human being who cares deeply about the military, and deeply about the grief that war causes," the president said during his end-of-the-year press conference at the White House.

FOX News' Kelly Wright contributed to this report.