Airspace
The US is giving control of some airspace controlled by Yokota Air Force Base back to Japan:
The airspace controlled by the United States will be reduced from the current six areas, which range in altitude from 7,000 meters to 3,700 meters, to five areas with altitudes ranging from 5,500 meters to 2,400 meters, a reduction of more than 20 percent of the current airspace, the sources said.
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U.S. permission is needed for aircraft to fly through Yokota’s airspace. Because of this, flights to and from Haneda and Narita airports usually fly high over the space or detour around it.
In January, the Construction and Transport Ministry said that a 40 percent reduction of Yokota’s airspace will benefit the economy to the tune of 19 billion yen annually, due to savings in airline fuel costs.
The partial return, to be accomplished by September 2008, is the first step in the process of giving full airspace control back to Japan. I have no way of knowing how the Ministry of Land, Infrastructure, and Transport came up with that figure, but airspace around Tokyo is notoriously overcrowded, and from various observation decks around the bay, you can clearly see planes stacked up for landing at Haneda. And though the Yomiuri doesn’t mention it, the move would fit into possible plans to make Japan increasingly responsible for its own military defense.