President Yoon Suk Yeol was set to depart for Lithuania on Monday for a North Atlantic Treaty Organization summit on a six-day trip that will take him to Poland for an official visit.

This will be Yoon's second time attending a NATO summit after the previous one held in Spain last year, demonstrating his commitment to building solidarity with like-minded nations to promote values, such as freedom, human rights and the rule of law.

The NATO gathering will be held in Vilnius on Tuesday and Wednesday, bringing together leaders from the 31 member states and partner nations, such as South Korea, Japan, Australia and New Zealand. Topics of discussion will include the war in Ukraine, cooperation between the military alliance and the Indo-Pacific region, and emerging security threats, according to the presidential office.

Yoon will hold at least 10 bilateral summits on the sidelines, including with the leaders of Norway, the Netherlands, New Zealand, Romania, Lithuania, Sweden, Slovakia, Estonia, Finland and Hungary. He will also meet with NATO Secretary-General Jens Stoltenberg.

A highlight will likely be Yoon's meeting with Japanese Prime Minister Fumio Kishida, which will come in the wake of the UN nuclear watchdog's conclusion that the planned release of treated radioactive water from the crippled Fukushima nuclear power plant into the sea meets international safety standards.

The report triggered a heated response in South Korea, with protesters opposing the discharge blocking the entryway of the Seoul airport through which International Atomic Energy Agency chief Rafael Mariano Grossi was due to arrive last Friday.

The presidential office has said Yoon will deliver the government's position to Kishida if the issue of the water discharge comes up during their meeting.

"If the Japanese side mentions it, (Yoon) will say what's necessary in keeping with the principle that we will place top priority on our people's health," a presidential official told reporters last week.

Yoon's attendance at the NATO summit will help strengthen cooperation with the alliance against North Korea's evolving nuclear and missile threats, and send a united message that North Korea's illegal acts will not be tolerated, according to Principal Deputy National Security Adviser Kim Tae-hyo.

Moreover, South Korea and NATO will adopt documents for bilateral cooperation across 11 sectors, including nonproliferation, cybersecurity and emerging technologies.

"We will share ways South Korea plans to contribute to peace in Ukraine, which is one of the most important issues in the international community, and realize in detail our global responsible diplomacy," Kim said during a press briefing last week.

"It will be an opportunity to expand the horizon of our diplomacy with Europe through direct exchanges with more leaders as we share the values of freedom, human rights and the rule of law, and further deepen cooperation with NATO states and partners," he said.

From Vilnius, Yoon will travel to Warsaw late Wednesday for a three-day official visit that will include a summit with President Andrzej Duda on ways to further develop the bilateral strategic partnership established between the sides in 2013.

He will hold separate meetings with the prime minister and with speakers of the lower and upper houses of parliament, and lay a wreath at the Tomb of the Unknown Soldier.

Talks will focus on expanding ties not only in trade and investment but also in strategic sectors, such as arms, nuclear power and infrastructure.

Yoon also plans to meet with officials from South Korean businesses operating in Poland, who are seeking to participate in reconstruction projects in post-war Ukraine, to discuss ways the government can support them.

An 89-person business delegation will accompany Yoon on the trip, representing companies in rechargeable batteries, arms and nuclear energy, as well as construction companies interested in participating in reconstruction projects in Ukraine.

This will be Yoon's first bilateral visit to a European nation since taking office. He will also be the first South Korean president to pay an official visit to Warsaw since Lee Myung-bak in 2009.

Kim, the deputy national security adviser, said this week's trip is expected to achieve three results: strengthening international security cooperation, expanding supply chain cooperation and promoting South Korea's bid to host the 2030 World Expo in the southeastern city of Busan.

On speculation Yoon could visit Ukraine during the trip and meet with President Volodymyr Zelenskyy, a presidential official told reporters there are no such plans.

Yoon will return home Saturday. First lady Kim Keon Hee will accompany him on the trip. (Yonhap)