The Republic of Korea's (ROK) unification ministry said on Monday that the country will take necessary actions to maintain dialogue momentum between the Democratic People's Republic of Korea (DPRK) and the United States. 

Lee Sang-min, spokesperson for the unification ministry, said both the DPRK and the U.S. are still willing to make progress through dialogue. 

The comment came after the DPRK's official Korean Central News Agency (KCNA) reported Sunday that it conducted a "very important test" at the Sohae Satellite Launching Ground on Saturday. 

The DPRK's Academy of National Defense Science reported the results of the "successful test of great significance" to the Central Committee of the Workers' Party of Korea. 

The test will "have an important effect on changing the strategic position of the DPRK once again in the near future," said the KCNA without further elaboration. 

The ROK spokesperson said they'll closely monitor the situation in the DPRK.

ROK President Moon Jae-in discussed the Korean Peninsula issue over the phone with U.S. President Donald Trump on Saturday, according to Seoul's presidential Blue House. 

The two leaders shared a view that the recent Korean Peninsula situation was severe, and agreed that dialogue momentum should be maintained towards achieving the early outcomes of the denuclearization talks between Pyongyang and Washington. 

Hours after the DPRK's announcement, Trump warned DPRK leader Kim Jong Un of losing "everything." 

"Kim Jong Un is too smart and has far too much to lose, everything actually, if he acts in a hostile way. He signed a strong Denuclearization Agreement with me in Singapore," Trump said on Twitter, referring to his first summit with Kim in Singapore in June 2018. 

Senior Pyongyang official Kim Yong Chol said on Monday that the DPRK leader may change his views toward Trump if he continues making "inappropriate, dangerous" comments, calling him an "impatient, old man." 

Kim Yong Chol, who was instrumental in arranging a failed second summit between Kim Jong Un and Trump, said the United States was ignoring a year-end deadline set for Washington to soften its stance in stalled denuclearization talks. 

"We have nothing more to lose," he said in a statement carried by the KCNA. 

The DPRK and the U.S. held working-level denuclearization negotiations in Stockholm in October, but the talks ended without progress. 

Pyongyang set its deadline for the denuclearization talks at the end of this year. Tensions have risen as both sides have pressured each other to make the first move.

The missile test was conducted after the DPRK repeatedly called on the U.S. to change its policy of insisting on Pyongyang's unilateral denuclearization and demanded relief from punishing sanctions but received no positive feedback. 

Pyongyang has previously warned it could take a "new path" amid the stalled talks with the U.S., which could mean going back to days of launching long-range or inter-continental ballistic missiles. 

(With input from Xinhua, Reuters)