A top general has surprised the U.S. military by announcing that Russia and the United States would sign a military cooperation deal when U.S. President Barack Obama visits Moscow next month.

"We have outlined the main issues of military cooperation for 2009 and beyond," the head of the General Staff, General Nikolai Makarov, said Friday after a 90-minute meeting with his U.S. counterpart, Admiral Michael Mullen.

"Our intention is that those documents should be signed when U.S. President Barack Obama arrives here in Moscow in July," Makarov said.

Mullen, the chairman of the U.S. Joint Chiefs of Staff, made no mention of any military agreement after the talks but said he was looking forward to the outcome of Obama's visit to Russia on July 6 to 8.

"I can't emphasize enough my belief that we need to work on these very hard challenges to improve security not just in Europe but in the world," Mullen said.

At the Pentagon, U.S. Defense Department spokesman Bryan Whitman said U.S. officials "had no idea" that Russian leaders were going to announce the intention to sign the agreement.

He called the expected agreement a sign of good will but would not discuss details.

"It's good for two countries to have strong, bilateral military-to-military relations," Whitman told reporters Friday. "We think it's valuable."

Makarov said he and Mullen discussed the U.S.-Russian talks on a successor to the 1991 START I arms control treaty, which expires Dec. 5, as well as U.S. missile defense plans, Afghanistan, Pakistan, North Korea and possible joint action against sea piracy.

Mullen, on his first visit to Moscow, said the meeting was frank and open.

The top military brass gave no further details about the talks.

The military talks follow renewed efforts by the two countries to reset relations that have become strained by events such as last year's Georgia war and NATO's expansion eastward.

"I'm very encouraged by our meetings and our mutual commitment to address these issues and strengthen our military-to-military cooperation," Mullen said.

"We have many common challenges … whether in Afghanistan or the challenges in missile defense, or in Iran or particularly for security in Europe," he added.