The former CIA chief pledged to give President Bush his honest advice on the costly and unpopular war, and said he would go to Iraq soon to see what U.S. commanders believe should be done to quell the growing violence.
"All of us want to find a way to bring America's sons and daughters home again," Gates said after taking the oath of office as defense secretary from Vice President Dick Cheney at a Pentagon ceremony. "But as the president has made clear, we simply cannot afford to fail in the Middle East. Failure in Iraq at this juncture would be a calamity that would haunt our nation, impair our credibility, and endanger Americans for decades to come."
Gates said he intends to travel to Iraq soon to hear the views of U.S. commanders on how to improve the situation, "unvarnished and straight from the shoulder." The remarks seemed to contrast with critics' complaints that the man he replaced, Donald H. Rumsfeld, did not listen enough to the advice of the military's top officers.
President Bush called Gates, 63, "the right man" for the multiple challenges the face in Iraq and in the global war on terrorism.
"We are a nation at war," Mr. Bush said. "And I rely on our secretary of defense to provide me with the best possible advice and to help direct our nation's armed force as they engage the enemies of freedom around the world. Bob Gates is the right man to take on these challenges. He'll be an outstanding leader for our men and women in uniform."
But Iraq will be just one of many critical situations facing Gates.
Although no orders have been issued yet, the Pentagon is planning a major buildup of naval forces in and around the Persian Gulf as a warning to Iran, CBS News national security correspondent David Martin reports.
The buildup would be a reaction to increasingly provocative acts by Iran.
Gates will also have his eye on Afghanistan, where the Taliban is making a comeback. On Monday, Gates called Afghanistan a pressing concern and said the progress made over the past five years is at risk, Martin reports.
Gates said that since his Senate confirmation earlier this month he has participated in meetings on Iraq at the White House, received briefings at the Pentagon and held in-depth discussions with the president on ways ahead in Iraq.
Gates takes office amid a wide-ranging administration review of its approach to the war. Mr. Bush said last week that he would wait until January to announce his new strategy, to give Gates a chance to offer advice.
Besides the wars in Iraq and Afghanistan, Gates faces other immediate challenges. One is the Army's proposal that it be allowed to grow by tens of thousands of soldiers, given the strains it is enduring from the two wars. Rumsfeld had resisted increasing the size of the Army or the Marine Corps; Gates' view is unknown.
Gates raised some eyebrows at his Senate confirmation hearing Dec. 5 by saying, when asked whether the U.S. was winning in Iraq, "No, sir."
It's not yet clear whether Gates intends to immediately shake up the Pentagon by firing generals or replacing senior civilian officials. He has asked Gordon England, the deputy defense secretary, to remain, but some have already announced their departures, including the top intelligence official, Stephen Cambone.
Gates, a Kansas native, joined the CIA in 1966. He left in 1974 to join the staff of the National Security Council until 1979, when he returned to the spy agency. He rose to deputy director for intelligence in 1982.
His 1987 nomination to head the CIA was scuttled when he was accused of knowing more than he admitted about the Iran-Contra affair. The Reagan administration secretly had sold arms to Iran in hopes of freeing hostages in Lebanon, and used the money to help the Contra rebels in Nicaragua.
Gates went to the White House as President Reagan's deputy national security adviser in 1989, then took over the CIA in 1991. He left Washington in 1993 and since August 2002 has been president of Texas A&M University.