The Democratic People's Republic of Korea (DPRK) will "soon take a next action" against the Republic of Korea (ROK), DPRK leader Kim Jong Un's sister Kim Yo Jong warned on Saturday, labeling the ROK as an "enemy." 

"I feel it is high time to surely break with the South Korean (ROK) authorities. We will soon take a next action," Kim Yo Jong, first vice department director of the Central Committee of the Workers' Party of Korea, said in a statement carried by the DPRK's official Korean Central News Agency (KCNA). 

"By exercising my power authorized by the Supreme Leader, our Party and the state, I gave an instruction to the arms of the department in charge of the affairs with enemy to decisively carry out the next action," she said. 

"The right to taking the next action against the enemy will be entrusted to the General Staff of our army," she added.

Kim Yo Jong's threats came amid renewed tension on the Korean Peninsula as Pyongyang blames Seoul for failing to stop anti-DPRK leaflets from being sent into the North. 

Jang Kum Chol, director of the United Front Department of the Central Committee of the Workers' Party of Korea, on Friday dismissed Seoul's promise to stop "defectors" from sending balloons carrying leaflets as "lip service" and warned that the DPRK will take "regretful and painful" retaliation soon against the ROK. 

Top security officials of the ROK convened an emergency meeting on Sunday to discuss responses to the DPRK's recent threats, Yonhap News Agency reported. 

The ROK's Unification Ministry called for the DPRK's compliance with the agreements signed between the two sides. The Defense Ministry said the ROK is closely watching the DPRK's military moves and will maintain a "staunch posture against all situations."

Pyongyang announced on Tuesday to cut off all inter-Korean communication lines. The joint liaison office set up in 2018 was shut down by the DPRK a few days earlier.

Relations between Pyongyang and Seoul warmed up in 2018 with three summits between DPRK leader Kim Jong Un and ROK President Moon Jae-in. The two sides signed the Panmunjom Declaration, which called for complete denuclearization of the peninsula and improving inter-Korean ties. 

However, inter-Korean cooperation has stalled since the second summit between the DPRK leader and U.S. President Donald Trump in Vietnam's Hanoi last year collapsed over differences on denuclearization and sanctions relief. 

A senior DPRK diplomat on Saturday urged the ROK to stop "nonsensical" talk about denuclearization, saying Seoul is not qualified to discuss or "poke their noses into" nuclear talks between Pyongyang and Washington.

On the other hand, Pyongyang also urged Washington to "keep its mouth shut" on inter-Korean affairs.

Commenting on the deterioration in relations between Pyongyang and Seoul as well as the stalled nuclear talks between Pyongyang and Washington, the Chinese Foreign Ministry called for "sustained peace and stability" on the peninsula and urged the United States to take "concrete actions" to address DPRK's "legitimate concerns." 

"The DPRK and the ROK share the same ethnic origin," Hua Chunying, spokesperson for the ministry, said at a regular press briefing on Tuesday. "As a close neighbor, China always hopes for sustained peace and stability on the peninsula." 

On Friday, which was the two-year anniversary of the first Trump-Kim summit in Singapore, Hua called for efforts to implement the consensus reached between the two leaders. Trump and Kim signed a joint statement at the historic meeting, pledging to build a peace mechanism and realize the complete denuclearization on the peninsula.

"Regrettably, however, the consensus has not been effectively implemented and the DPRK-U.S. talks have come to a deadlock," she said.  

"Although there are many reasons, China believes that the main sticking point is that the DPRK's legitimate concerns have not been given due attention and resolved, and the denuclearization measures taken by the DPRK have not been responded to accordingly," she added. 

China and Russia proposed lifting some sanctions against the DPRK to the United Nations Security Council last December, calling on the U.S. and the DPRK to "meet each other halfway." 

"Building mutual trust and breaking the impasse on the peninsula requires concrete actions," Hua said at Friday's press conference. "The U.S. side should take concrete actions to implement the consensus reached by the DPRK and the U.S. leaders, respond to the DPRK's legitimate concerns on development and security, and safeguard the hard-won situation of amelioration and dialogue on the Korean Peninsula."