The cost of moving the US Marine Corps Air Station Futenma is also likely to increase from 350 billion yen ($3.2 billion) to at least 930 billion yen, the Japanese Kyodo news agency said.
The delay is reportedly due to the fact that the soft seafloor needs to be reinforced as part of the reclamation.
At the beginning of this year, more than 72 percent of Okinawa residents voted in a referendum against the base relocation plan. In April, the United States and Japan reconfirmed their plans to move the base despite objections from the public.
Futenma was named to be "the world's most dangerous base in the world" by then-US Secretary of Defence Donald Rumsfeld in 2003, who flew over the base and observed that it was right in the middle of an urban settlement surrounded by schools and houses. This is in direct violation to the US Department of the Navy's safety standards, which requires that any airbase runway must be clear of all construction other than airport lighting at each of its ends.
Okinawa, which accounts for only 0.6 percent of Japan's territory, hosts over 30 US military installations — more than 70 percent of their total number in Japan — and nearly a half of the around 50,000 US forces deployed in the country.
