Political wrangling by Japan's new government over plans to move a major U.S. Marine base on Okinawa has opened a wide rift in Washington's most important Asian alliance ahead of President Barack Obama's visit later this week.

The relocation of Marine Corps Air Station Futenma is the centerpiece of a sweeping realignment plan for the 47,000 U.S. troops in Japan.

Washington and Tokyo agreed three years ago to move the airstrip, which is located in a crowded city and for decades has stood as a symbol of the heavy burden the tiny island of Okinawa has to bear to support Japan's military alliance with the United States.

But, in one of its first significant diplomatic moves, Japan's newly elected liberal administration has put the whole deal on hold.

Prime Minister Yukio Hatoyama, who took office in September, has refused to accept any deadlines for signing off on the deal to move Futenma to a more remote part of Okinawa. With no progress likely during his Friday meeting with Obama, he was expected to focus on Japan's offer of $5 billion in new aid for Afghanistan and to discuss climate change and economic issues.

Obama tried to smooth over the dispute in remarks before his departure.

"I'm confident that once that review is completed that they will conclude that the alliance that we have, the basing arrangements that have been discussed, all those things serve the interests of Japan," Obama told NHK, Japan's public broadcaster.

Even so, the two sides remain so far apart on the Futenma move that Senior White House Asia adviser Jeffrey Bader told reporters Monday that Washington does not believe the base issue is "ripe for resolution or a focus" of the two-day visit, which was delayed by a day for Obama to attend a memorial service for victims of the Fort Hood shooting.

The U.S. security relationship with Japan is more crucial than ever, with China's influence and military strength rising rapidly and North Korea honing its nuclear and missile technologies.

But senior American officials say that as long as the Futenma move is on hold, they can't move forward with a bigger effort to reshape their footprint in the Pacific _ including a plan to move 8,000 Marines from Okinawa to the U.S. Pacific territory of Guam.

"What seemingly has been brought to the fore is the commitment on the part of this government to an agreement that we made with the Japanese government, between our two countries," Adm. Mike Mullen, chairman of the joint chiefs of staff, said before a recent meeting with Japan's foreign minister. "We think it is urgent to examine and commit as rapidly as possible."

Before taking office, Hatoyama said he wants the base moved off Okinawa or pulled out of Japan completely. He has since essentially frozen plans to move the base to a location farther north on Okinawa by 2014 and vowed to "fundamentally review" a broader effort to revitalize the U.S. military's presence in Japan.

Hatoyama's position reflects long-standing skepticism among Japanese progressives about whether the country needs so many U.S. troops, although most generally agree the presence has contributed to regional stability.

Hatoyama has tried not to upset the U.S., but he is also keenly aware of his campaign promises to lighten the load on Okinawa, which makes up less than 1 percent of Japan's land but hosts about 75 percent of all the U.S. bases.

"This is an issue that needs careful consideration," Hatoyama said under sharp questioning in parliament last week by members of the staunchly pro-U.S. Liberal Democratic Party, which ruled Japan for most of the postwar period and signed off on the 2006 Okinawa deal. "We must not hurry to a decision."

That stance has not gone over well in the Pentagon.

In two high-profile and unusually pointed visits intended to pave the way for Obama's two-day visit, Mullen and Defense Secretary Robert Gates bluntly told Tokyo they wanted Japan to sign off on the realignment plan in time for the president's arrival. Continued...