The United States has expressed concern about Japan’s desire to acquire the ability to attack enemy bases in an overhaul of defense policies pursued by Prime Minister Shinzo Abe, a government source said in Tokyo.

One of the American officials attending bilateral talks on foreign and defense policy cooperation late last month in Tokyo asked the Japanese side to consider the possible negative fallout on neighboring countries if the Abe administration embarks on such a policy shift, the source said Tuesday.

The U.S. official conveyed Washington’s message that Tokyo should not further worsen relations with China and South Korea, which have been plagued for months by territorial rows, as well as the issue of Japan’s wartime aggression.

The government is currently compiling new defense guidelines, and an interim last month stated that Japan should take on a greater regional security role and reinforce its defense capabilities, including enabling the Self-Defense Forces to attack enemy bases.

The proposal comes as Japan faces North Korea’s missile and nuclear threats. The government is planning to agree within the year on the long-term guidelines, which would also mention the need to counter China’s increasing military assertiveness.

At the working-level talks July 25, Japanese officials briefed their American counterparts on the interim report. The U.S. officials called for further explanation on what countries and measures Japan is considering while seeking to acquire the ability to strike enemy targets, the source said.

The U.S. side also said that Japan must carefully work to obtain understanding for the policy from neighboring countries, and the Japanese officials replied they will make efforts to that end, the source said.

“Japan needs to enhance its ability to respond to ballistic missile attacks in a comprehensive manner,” the interim report said in reference to the option of attacking enemy bases.

Some officials in Tokyo have said such an attack could possibly use U.S.-made Tomahawk cruise missiles. But other officials say difficulties remain in introducing such a measure, including the need to clarify what would be considered self-defense.

“We cannot easily decide on that,” a senior Defense Ministry official said.