Pentagon chief Robert Gates did not specifically mention the controversy over the Futenma base, a major U.S. Marines hub, during brief remarks with Japanese Foreign Minister Katsuya Okada.
But the defense secretary made clear that the Obama administration would frown on any action by Tokyo to block a new runway at another base on Okinawa when Futenma is closed.
"As your government exercises its new responsibilities, I want you to know the United States stands with you," Gates told Okada at the start of their half-hour meeting in Tokyo. "And we are committed to advancing and implementing our agreed alliance transformation agenda."
Okada also did not delve into any specific topics when he told Gates the administration of newly-elected Prime Minister Yukio Hatoyama would seek a "deeper and sustainable" relationship with the U.S.
"Of course, we have a lot of challenges," Okada added.
At issue is the fate of the air field in the wake of Hatoyama's election last month.
Three years ago, U.S. and Japanese officials agreed to shift 8,000 Marines in Okinawa to the U.S. territory of Guam and to move the Futenma air field base to Camp Schwab, also on the southern Japanese island.
But some members of Hatoyama's government want all remaining U.S. troops moved out of Japan altogether. Okinawa residents have complained that the military bases cause too much noise and crime.
U.S. officials hope to resolve the issue by the time President Barack Obama arrives in Japan early next month. Gates will meet with Hatoyama on Wednesday.
Earlier, Gates said he did not expect Japan to renege on the agreement and said there "are no alternatives to the arrangement that was negotiated."
(Left: Marine Corps helicopters and transport planes are seen at Futenma Marine Corps Air Station next to Okinawa residential quarters in this February 2007 file photo.)
He said that other, unidentified locations for the air field that were reviewed by the U.S. and Japanese governments were either politically or operationally impossible.
Gates said he had no problem with Hatoyama's decision to review the agreement, and cited "some flexibility" in terms of where, precisely, a new runway might be built at Camp Schwab. But ultimately, Gates said, the runway location is a matter for the local Okinawa government to decide with Tokyo.
The United States is Japan's key military ally, and an estimated 50,000 American troops are deployed there.
The issue of Japan withdrawing two of its naval ships from the Indian Ocean - tankers that have been used as refueling pit stops for Afghanistan-bound allies - will also be discussed over the next two days, Gates said.
However, it was unclear whether Gates thought he could reverse that decision.
"A number of countries benefit more from the refueling than the United States does," Gates said. "So I don't see the refueling as being a favor to the United States, but rather a contribution that the Japanese have made that is commensurate with its standing in the world as the second-wealthiest country and one of the great powers."
He added, "I'm sure we'll talk about it."
By Associated Press Writer Lara Jakes