MANILA, Philippines -- President Yoon Suk Yeol and his Philippines counterpart Ferdinand Marcos Jr. agreed on South Korea's greater participation in the Southeast Asian country's bid to boost military readiness, build infrastructure and introduce nuclear energy, according to Yoon's office on Monday.

During the bilateral meeting of Yoon and Marcos, Seoul and Manila elevated their ties to a Strategic Partnership.

The declaration will "open a new chapter of our partnership," Yoon said in a joint press conference with Marcos after the summit at the Malacanang Palace in Manila, the Philippines' capital. Yoon also said the area of strategic ties will focus on security, economy and sustainability.

The Philippines has become the fifth ASEAN member country with which South Korea conducted such a partnership, according to Yoon's office.

Under the joint declaration, both countries will strengthen security and defense engagements through military exercises.

An official from the presidential office of South Korea said on condition of anonymity that Manila seeks greater participation of South Korean military forces in multilateral exercises in the Indo-Pacific region.

The source added this builds on Seoul's ongoing participation in exercises such as Balikatan, a joint exercise between the Philippines and the United States; US-led Pacific Partnership; and US-Philippines joint exercise Kamandag, also known as the Cooperation of the Warriors of the Sea.

As to the possibility that military cooperation could irk China, given the Philippines' long-standing territorial dispute with China in the South China Sea, the official said, "(Seoul) has enough grounds to participate in exercises to ensure regional peace and maritime order. Therefore, we see there is no big issue about the matter."

South Korea and the Philippines will also enhance the "special partnership" that would allow South Korea to support Phase 3 of the Modernization Program of the Armed Forces of the Philippines, a five-year plan in effect since 2023.

During Manila's two previous five-year phases of the modernization program, implemented during the 2013-2022 period combined, South Korea exported an undisclosed value of military assets such as light combat aircrafts, anti-ship cruise missiles, as well as frigates, corvettes and patrol vessels.

The two countries' maritime law enforcement authorities also signed a document to tackle international maritime crimes and share related information. Marcos said the aim was to pursue "mutual maritime interest including international maritime order and safety in the Asia-Pacific region"

Alongside the agreement between the coast guards of the two countries, they will closely cooperate to address North Korea's illicit trade by sea and air concerning Pyongyang's weapons development, according to Yoon's office.

This comes amid the Philippines' territorial conflicts with China, which have continued despite a 2016 ruling at the international tribunal unanimously in favor of the Philippines.

During the summit, Marcos stressed a need for the concerted effort to preserve the international maritime order under the UN Convention on the Law of the Sea, which set the legal basis for the 2016 ruling.

Moreover, Yoon said the summit paved the way for South Korea's greater participation in infrastructure projects, as enshrined under Marcos' "Build Better More" initiative during his six-year term that started in 2022.

Yoon said at the conference that the two countries agreed to "expand South Korean companies' participation in the Philippines' various infrastructure projects."

Yoon also said the two development loans via the Economic Development Cooperation Fund announced Monday will allow South Korean firms to "play pivotal roles" in the infrastructure projects in the Southeast Asian country.

Under the agreements, South Korea will provide a combined $1.95 billion in infrastructure development loans to two projects in the Philippines.

The $950 million loan will go to the construction of the 7.9-kilometer road as part of the project to build the Laguna Lakeshore Road Network, spanning 37.5 kilometers on the outskirts of Manila. Also, a $1 billion loan will be provided to build a 13-kilometer bridge to connect the two islands of Panay and Guimaras, as part of the 32.47-kilometer project connecting three islands of Panay, Guimaras and Negros.

These would amount to the two biggest loans extended since the launch of the EDCF, said Park Chun-sup, senior presidential secretary for economic affairs.

Yoon also stressed the need for the Philippines to introduce carbon-free energy, as the two countries recognized the Philippines' transition to clean energy as key to climate change mitigation and sustainable growth. Marcos said the normalization of the plant could be a matter of "energy security."

Under an MOU signed between South Korea-based Korea Hydro and Nuclear Power and the Philippines' Department of Energy, a South Korean entity will conduct a six-month feasibility study on the rehabilitation of the Bataan Nuclear Power Plant, about 70 kilometers west of Manila.

This will enable South Korea to explore the chance to rehabilitate the 621-megawatt nuclear power reactor on which construction was halted in 1986.

A total of 20 MOUs were signed during Yoon's trip, according to Seoul.

Before the summit, the presidential office said Yoon laid a wreath at the Jose Rizal monument in Rizal Park in Manila, in memory of the activist at the end of the Spanish colonial rule in the late 19th century.

Following the summit, Yoon also attended a business forum in Manila, along with some 300 business leaders from both countries, including Lee Jae-yong, executive chairman of Samsung Electronics; Walter Cho, chairman and CEO of Korean Air; and LS Chairman Koo Ja-eun.

Later Monday, Yoon headed for Singapore for a state visit until Wednesday, as Yoon is poised to attend the ASEAN summit later this week in Vientiane, Laos.