Speaking to Congress, the U.S. Defense Secretary Robert Gates said he is planning to boost American forces in Afghanistan and is planning to improve working relations with Russia.

Russia strongly opposes U.S. plans to place missile defence systems in Eastern Europe, including plans for the Czech Republic to host a radar base while Poland would have an anti-missile system within its country.

Washington says the purpose of the defence system is intercepting possible missile attacks from ‘rogue states’ such as Iran and North Korea, but Russia sees the program as a threat to its security.

“I think there are some real opportunities here. Russia is clearly not the target of our missile defence endeavors. Iran is. We have a mutual concern there. While the Russians have an unrealistic view of the timeline for when an Iranian missile is arranged to attack, much of Russia and much of Europe will be vulnerable. But I am very open to the idea of further cooperation on missile defence with Russia,” Robert Gates said.

Gates also said that when Russian Prime Minister Vladimir Putin was president he showed signs of interest in working together.

Said Gates: “I had the distinct impression when I presented a range of opportunities for cooperation and transparency to President Putin that he was actually taken by some of the ideas.”

Admiral Mike Mullin, Chairman of the Joint Chiefs of Staff, was cautiously optimistic about future relations.

“I talk to my Russian counterpart and I'm encouraged by those discussions. But there's still a lot of things that we don't see eye to eye on. I think we're going to need to be engaged with them to figure out answers to that,” said Admiral Mullin.

“There are opportunities to discuss common interests…Afghanistan and Iran are common interests, as is stability in the Middle East,” he added.

Defense Secretary Gates also said the U.S. military could send two more brigades to Afghanistan by late spring and a third by late summer.

Gates called Afghanistan America's “greatest military challenge” and coordinating the fight against the insurgency has been “less than stellar.”

He emphasized that more troops could be sent once the Defense Department is able to put a larger infrastructure in place to support them.

Earlier, U.S. President Barack Obama indicated he wants to shift more military resources from Iraq to Afghanistan.