South Korean President Lee Myung-Bak on Wednesday received a briefing from top US commanders on the threat posed by North Korea in a visit to the Pentagon, officials said.

Defense Secretary Leon Panetta and the US military's top officer, General Martin Dempsey, along with chiefs of all the armed services hosted Lee in the famed secure conference room known as "The Tank," in what officials said was a rare invitation to a foreign head of state.

"Today's briefing represents the first time in recent history that a foreign head of state has been briefed by the service chiefs in The Tank," said spokesman Captain John Kirby.

Lee heard "an updated North Korea threat assessment" from the top brass, he said.

For decades, the senior officers in charge of the Army, Air Force, Navy and Marine Corps have hashed out battle plans and budget wars in the windowless "Tank."

Lee's visit to the American military's headquarters was part of an elaborate display of official hospitality for the South Korean leader this week, with President Barack Obama planning a state banquet for him on Thursday.

Lee's talks at the Pentagon came hours before the US Senate approved a long-stalled trade deal with South Korea, which Obama said will boost exports and create jobs.

In talks with Lee and Defense Minister Kim Kwan-Jin, Panetta "discussed a range of security-related alliance issues, including how best to work together to improve alliance capabilities and deterrence measures," Kirby said.

Panetta then later held more talks with his South Korean counterpart focusing on security on the Korean peninsula.

The Pentagon chief affirmed that the US alliance with South Korea "is a cornerstone of stability in Northeast Asia and has never been stronger," Kirby said.

The two also discussed annual US-South Korea security talks in Seoul that Panetta is scheduled to attend on October 28 as part of a tour of Asia later this month.