Japan may export the ship-launched Standard Missile-3 system, a change from the country's current ban on selling arms and weapons.

Raytheon's Standard Missile-3 block 2A system is an advanced version of the SM-3 series jointly under development with the United States and other countries.

The apparent move comes after a request last October by U.S. Defense Secretary Robert Gates to Japan's Defense Minister Toshimi Kitazawa. Japan is set to receive the first of the missiles in 2018.

The United States is expecting an answer by the end of the year, a report in Japan Times newspaper said.

The 21-foot SM-3 missile, designated RIM-161A in the United States, is a major part of the U.S. Navy's Aegis Ballistic Missile Defense System and is a compliment to the Patriot missile.

Speed of the latest SM-3 is around 6,000 mph within a ceiling of 100 miles and a range of 270 nautical miles.

The booster is the United Technologies MK 72 solid-fuel rocket and the sustainer is the Atlantic Research Corp. MK 104 dual-thrust solid-fuel rocket.

The third stage is Alliant Techsystem's MK 136 solid-fuel rocket.

The missile's kinetic warhead is a Lightweight Exo-Atmospheric Projectile, a non-explosive hit-to-kill device. The launching ships will be updated with Aegis LEAP Intercept computer software and hardware.

In 1967, Japan banned the export of arms and weapons to other countries but excluded the United States from the ban in 1983, allowable under a bilateral security pact.

Japan has been a participant in the U.S. ballistic missile defense program since August 1999 when the Japanese government agreed to conduct cooperative research.

Deployment of the SM-3 has been a central focus of U.S. President Barack Obama's planned protection against short- and medium-range missile threats, including from Iran, announced last September.

In February the Romanian Supreme Defense Council said the country would take an SM-3 interceptor as a "first step" in implementing the Obama administration's revised missile defense plan.

U.S. Assistant Secretary of State for Public Affairs P.J. Crowley said at the time Romania's decision extends the area of missile defense coverage into southern Europe. The interceptor is expected to be operational by 2015.

Last month Tokyo complained to North Korea about the hard-line communist state's test-firing of seven missiles into the Sea of Japan.

The Japanese government filed the official diplomatic complaint through Chinese channels in Beijing as the South Korean Joint Chiefs of Staff spotted the seventh missile firing of the day, the South Korean news agency Yonhap reported at the time.

Japanese Chief Cabinet Secretary Takeo Kawamura said in a statement, "It is a serious act of provocation against the security of neighboring countries, including Japan, and is against the resolution of the U.N. Security Council."

At the same time successive Japanese governments have been sensitive to any idea that the U.S. military stations missiles with nuclear warheads on Japanese territory because of country's experience in the World War II as a target for atom bombs.