Munich, Germany ? Pentagon chief Robert Gates responded Sunday to Vladimir Putin’s assault on U.S. foreign policy by saying “one Cold War is enough” and that he would go to Moscow to try to reduce tensions. Gates also sought more allied help in Afghanistan.

He delivered his first speech as Pentagon chief at a security conference in Germany and then flew to Pakistan to discuss fears of a renewed spring offensive by Taliban fighters in neighboring Afghanistan.

Pakistan, a close U.S. ally in the fight against terrorism, has faced charges that the Taliban militia stage attacks from Pakistan against Afghan government troops and NATO- and U.S.-led coalition troops.

Gates’ rebuke of the Russian president relied on humor and some pointed jabs.

“As an old Cold Warrior, one of yesterday’s speeches almost filled me with nostalgia for a less complex time. Almost,” Gates said. Then, as the audience chuckled, the defense secretary said he had accepted Putin’s invitation to visit Russia.

“We all face many common problems and challenges that must be addressed in partnership with other countries, including Russia,” Gates said. “One Cold War was quite enough.”

In his speech Saturday, Putin blamed U.S. foreign policy for inciting other countries to seek nuclear weapons to defend themselves from an “almost uncontained use of military force.”

The Russian leader said “unilateral, illegitimate actions have not solved a single problem, they have become a hotbed of further conflicts” and that “one state, the United States, has overstepped its national borders in every way.”

Gates also made an urgent call for NATO allies to live up to their promises to supply military and economic aid for Afghanistan.

“It is vitally important that the success Afghanistan has achieved not be allowed to slip away through neglect or lack of political will or resolve,” Gates said. Failure to muster a strong military effort combined with economic development and a counternarcotics plan “would be a mark of shame,” he said.

Gates also said that prisoner abuse scandals in Iraq and Guantanamo Bay, Cuba, and other mistakes had damaged America’s reputation. It will take work, he said, to prove that the U.S. still is a force for good in the world.

While he did not mention the war in Iraq, Gates told officials at the security conference that U.S. leaders must do a better job of explaining its policies and actions.

For the past century, he said, most people believed that “while we might from time to time do something stupid, that we were a force for good in the world.”

Many continue to believe that, Gates said. But, he added, “I think we also have made some mistakes and have not presented our case as well as we might in many instances. I think we have to work on that.”

In other comments, he said the Bush administration would like to close the Guantanamo Bay detention facility, but there are some terrorists there who should never be let free. Gates also said detainee trials there would be conducted in the open and with adequate defense for the prisoners.