In the first visit to the Pentagon by a Russian defense minister in five years, Serdyukov was greeted by a military band and color guard before heading into talks here at the Pentagon with Gates and other U.S. officials.

After several hours of meetings, the Russian defense minister and the U.S. defense secretary signed two documents on defense cooperation, including a memorandum that Gates said replaces an outdated 1993 accord.

"It underscores that defense cooperation is an important element of strengthening the wider U.S. - Russian relationship, especially now when our two countries confront many similar security threats and challenges," said Robert Gates.

In addition to efforts to streamline their respective militaries, the Russian defense minister said discussions included the sensitive issue of missile defense.

"We have discussed in detail the issues pertaining to the national missile defense and the challenges facing us and the progress made by our joint work group in this aspect," said Anatoly Serdyukov.

A senior defense official told reporters that Gates thanked his counterpart for Moscow's permission to allow the U.S. military and NATO to move troops and supplies across Russian territory for the war in Afghanistan.

The deal has eased the pressure on supply routes through restive and flood-ravaged areas of Pakistan.

The official says both sides also discussed issues in the Middle East, with Gates expressing appreciation for Russia's support for sanctions against Iran because of its nuclear program.