Mattis' remarks came amid speculation that the emerging peace mood, coupled with US President Donald Trump's apparent transactional approach to statecraft, could lead to a drawdown -- or even the pullout -- of the 28,500 US troops in South Korea.

Trump's failure to codify the US demand for the CVID in his June 12 summit agreement with North Korean leader Kim Jong-un also stoked worries about a possible retreat from it.

Mattis also touched on the allies' recent decision to suspend a major combined exercise, casting it as an effort to facilitate diplomacy on North Korea's denuclearization.

"The recent decision to suspend the Freedom Guardian exercise creates an increased opportunity for our diplomats to negotiate, increasing the prospects for a peaceful solution on the Korean Peninsula," he said. "At the same time, the US and ROK forces remain united, vigilant and ready to defend against any challenge."

Song called his talks with Mattis "timely," saying the allies stand at a "crucial turning point that may put behind a dark history of confrontation and lead to a new history of peace and cooperation."

"The South and the US will do their best to ensure that this precious opportunity will definitely lead to peace and stability not only on the peninsula but also in Northeast Asia and the world," Song said.

"Secretary Mattis and I plan to make solid efforts in the defense sector while maintaining close cooperation with pinpoint accuracy in our efforts to realize our shared goal," he added.

Song also said that amid the changing security environment, the alliance will "grow ever stronger, more mature and mutually complementary."

"In the midst of this, the US Forces Korea as a symbol of the South Korea-US alliance will always be with the Republic of Korea military," he added.

At the meeting, Song and Mattis were expected to discuss the recently suspended combined military exercises and the envisioned transfer of wartime operational control.

The meeting followed the recent decision by Seoul and Washington to indefinitely suspend the Korea Marine Exercise Program and the annual combined Ulchi Freedom Guardian exercises, which were slated to kick off next month and in August, respectively.

Following the decision, the need has arisen for them to coordinate the allies' stances over how to carry out their regular exercises while not undermining the current momentum for dialogue with North Korea over its denuclearization.

The suspension has sowed concerns that the allies could, after all, halt all other combined exercises in a way that would attenuate their longstanding security partnership and deterrence capabilities.

But US Forces Korea Commander Gen. Vincent Brooks dispelled those concerns Wednesday, noting that the suspension appears to be intended to help the allies build trust with the North and add "greater effectiveness" in diplomacy on the communist regime.

The envisioned "conditions-based" transfer of wartime operational control was also expected to be discussed at the Song-Mattis talks.

During their Security Consultative Meeting slated for autumn in Washington, the two sides are expected to agree on a broad road map for the transfer, which observers expect to come in the early 2020s. (Yonhap)