-Editorial-

TOKYO — Both to deter North Korea's military provocations and to ensure regional stability in Asia, it's vital that the United States and South Korea maintain their solid alliance. South Korea should be mindful not to get too close to China, or risk weakening its collaboration with the United States.

U.S. President Barack Obama held talks with his South Korean counterpart Park Geun-hye in Washington, during which they adopted a joint statement focused on their cooperation to get Pyongyang to abandon its nuclear and missile programs.

The statement warns that additional sanctions will be imposed on North Korea should the country push through with launching a ballistic missile or conducting a nuclear test in violation of UN Security Council resolutions.

Since last summer, North Korea has heightened military tensions between South and North, while also hinting at the possibility of conducting nuclear tests.

It's significant that Obama confirmed the need to strengthen the U.S.-South Korea relationship during a joint press conference. "The commitment of the United States to the defense and security of the Republic of Korea will never waver," he said.

Yet it can't be denied that the "close alliance" between the two countries has been largely choreographed, because the heightened distrust within the United States regarding South Korea's inclination toward China needed to be denied.

Park decided on South Korea's participation in the China-led Asian Infrastructure Investment Bank, and attended the military parade China held to mark the anniversary of its World War "victory over Japan."

"I believe that we South Korea and the United States make natural partners," Park said at the press conference regarding the Trans-Pacific Partnership trade negotiations, in which member countries such as Japan and the United States recently reached a broad agreement. This statement indicated Seoul's intention to join the TPP, and was probably aimed at mitigating U.S. concern.

Obama said at the press conference that if China fails to abide by international rules, "We expect the Republic of Korea to speak out on that."

Obama's remark was apparently made in consideration of China's self-serving maritime advances in the East and South China seas — but Park made no reference to this.

It remains unclear whether South Korea will modify its diplomatic stance toward China.

The amount of bilateral trade between China and South Korea exceeds the sum of its trade with the United States and Japan. We can understand Seoul attaching importance to China economically, but shifting its priorities from Washington to Beijing in the realm of security could destabilize the region.

During a speech made earlier in Washington, Park said she intends to hold her first full-fledged talks with Prime Minister Shinzo Abe on the occasion of the trilateral summit among Japan, China and South Korea in early November.

Since she took office, Park made it a condition that she would hold summit talks with Japan if progress was made on the issue of so-called "comfort women" victimized during World War II.

Park appears to have agreed at last to Washington's repeated urging to improve bilateral relations between Japan and South Korea.

But, Park emphasized, "The summit can have substantial meaning if we see some progress on the issue of comfort women."

Unless Park changes her diplomatic posture of giving too much weight to issues related to historical perception, it will be difficult for Japan and South Korea to effectively deal with the mountain of pending issues. It will be impossible to realize the close trilateral cooperation among Japan, the United States and South Korea that Washington hopes to see.

*This editorial first appeared in Sunday's edition of Yomiuri Shimbun.