This photo, provided by North Korea's Korean Central News Agency, shows the launch of the North's new "Chollima-1" rocket, allegedly carrying a military reconnaissance satellite, "Malligyong-1," at Tongchang-ri, Cholsan County, North Pyongan Province, North Korea, June. 1. Yonhap

South Korea's top security adviser said Sunday he saw a high possibility that North Korea is likely to launch another spy satellite before the end of this year, though signs of an imminent launch have yet to be detected.

"There is a high possibility that North Korea will launch a reconnaissance satellite before the end of this year," National Security Adviser Shin Won-sik said in an interview with Yonhap News Television.

The assessment came as North Korea has vowed to launch three satellites this year following its successful launch in November last year. The North launched another satellite in late May, but the rocket exploded shortly after takeoff.

Noting that it has taken time for the North to integrate the command system for a new satellite launch system since its latest attempt in May, Shin said that final preparations are under way.

On North Korea and Russia's deepening ties, Shin said the possibility of North Korean leader Kim Jong-un visiting Russia cannot be ruled out.

"It could be a reciprocal visit for Russian President Vladimir Putin's trip to North Korea in June, or it could be a visit for Putin to thank the North on its troop deployment," Shin said, adding the possible visit should be closely monitored as "sensitive matters" could be addressed.

Last week, South Korea's spy agency said that North Korean Foreign Minister Choe Son-hui engaged in sensitive discussions with Putin during a visit to Moscow and added the North's leader could make a visit to Russia.

During their meeting in Pyongyang in June, Kim and Putin signed a comprehensive strategic partnership, a landmark pact that includes a mutual defense clause.

Shin said the recent assessment by the International Atomic Energy Agency (IAEA) that the uranium enrichment facility Kim visited in September appears to be an undeclared extension inside its main nuclear site near Pyongyang is "mostly true," adding more analysis is necessary.

On the possibility of President Yoon Suk Yeol holding talks with U.S. President-elect Donald Trump, Shin said Trump has suggested at least three times meeting before his inauguration.

"I understand that Trump's side has established the rules on not meeting foreign leaders before inauguration in consideration of appointment, domestic issues and preparations for inauguration," Shin said, stressing both sides have been engaging in close communications.

On relations with China, Shin said the possibility of Chinese President Xi Jinping visiting South Korea on the occasion of the Asia-Pacific Economic Forum (APEC) meeting set to be held in South Korea next year is high.

"Because China is the host country for 2026, it further raises such possibility," Shin said. (Yonhap)