U.S. President Barack Obama stressed the "critical importance" of trilateral cooperation with allies South Korea and Japan in ensuring peace and stability in the region, the White House said Thursday.

Obama made the remark during a meeting with Japanese Prime Minister Shinzo Abe on the sidelines of the Asia-Pacific Economic Cooperation summit in the Philippines.

"President Obama noted the critical importance of a strong trilateral relationship among the United States, Japan, and the ROK to ensure peace and stability in the region," the White House said in a readout provided in a pool report.

Obama also commended Japan for trying to improve ties with South Korea and China, it said.

"The two leaders reaffirmed their determination to work together and with other partners in Asia and the Pacific to strengthen the rules-based regional order, including by upholding the principles of customary international law, freedom of navigation and overflight, unimpeded lawful commerce, and peaceful resolution of disputes," the White House said.

The two leaders also agreed on the importance of strengthening defense cooperation under the new Defense Guidelines between the two countries as well as on moving forward with plans for the realignment of U.S. forces in Japan, the White House said.

The guidelines, which were revised in April, are designed to significantly expand Japan's military role in the region and beyond. It centers on Japan exercising its "collective self-defense" right that empowers Japan's Self-Defense Forces to fight alongside the U.S. even when the country's not under attack. (Yonhap)