TOKYO (Kyodo) -- Prime Minister Shigeru Ishiba on Thursday expressed hope that the recent thaw in ties between Japan and South Korea will continue despite his counterpart facing a backlash at home for his temporary declaration of martial law.

President Yoon Suk Yeol "has been striving to improve ties with Japan based on his conviction that doing so would serve the interests of South Korea," Ishiba said. "We believe such efforts by President Yoon should not be undermined no matter what."

Yoon faces growing pressure to resign after his short-lived martial law declaration Tuesday night caused domestic turmoil and sent shockwaves beyond democratic South Korea. Opposition parties in the country are seeking to impeach the president, who took office in 2022.

Bilateral ties have been improving since Yoon became president, after sinking to their lowest point in years over issues related to Japan's wartime rule of the Korean Peninsula and a territorial dispute.

Building on the momentum seen when his predecessor was in office, Ishiba has already met with Yoon twice since becoming prime minister in October.

Ishiba's remarks at a parliamentary session came in response to a question by former Prime Minister Yoshihiko Noda, who leads the main opposition Constitutional Democratic Party of Japan.

Noda stressed the importance of cooperation between the Asian neighbors, and trilaterally with their common ally the United States, to cope with threats posed by North Korea.

Pyongyang has been pursuing nuclear and missile development while deepening military cooperation with Russia in the wake of its invasion of Ukraine.

Japan's top government spokesman Yoshimasa Hayashi said Japan and South Korea are "important neighbors" who can jointly tackle global challenges as partners.

"We are closely monitoring developments in South Korea with particular and grave concerns," Hayashi, who is chief Cabinet secretary, told a regular press conference.

Japan will decide on how to proceed with relations with South Korea "appropriately" depending on how the situation develops, he said.