Defense Minister Lee Jong-sup on Thursday reaffirmed South Korea's commitment to further strengthening its alliance with the United States, pointing to the "very grave" security threats from North Korea.

He was speaking at a breakfast meeting with former and current South Korean and US officials, as concerns have grown about the possibility of the North carrying out its seventh nuclear experiment at the Punggye-ri testing site.

"Due to the advances in North Korea's nuclear and missile capabilities, and its preparations for a seventh nuclear test, the security situation on the Korean Peninsula is very grave," Lee said. "Our military will always strengthen the South Korea-US alliance further and firmly defend South Korea."

The Korea-US Alliance Foundation and the Korea Defense Veterans Association hosted the gathering, titled "National Prayer Breakfast Meeting for Strengthening National Security and the ROK-US Alliance." ROK stands for South Korea's official name, Republic of Korea.

At the meeting, Foreign Minister Park Jin also delivered a speech highlighting Seoul's concerns over Pyongyang's evolving military threats.

Park pointed out that the North's military capabilities are threatening peace not only on the Korean Peninsula but also in the world, and that the allies are working together toward the shared goal of the North's complete denuclearization ultimately for the sake of "sustainable peace."

Attendees at the meeting included Rep. Kim Jin-pyo, the main opposition Democratic Party's candidate for National Assembly speaker, and Christopher Del Corso, the charge d'affaires ad interim at the US Embassy in Seoul. (Yonhap)