South Korea's ruling Saenuri Party said Tuesday that North Korea's nuclear and missile threats cannot be stopped by diplomatic channels alone, adding a U.S. advanced missile defense system is vital to protecting the country and urged the opposition to work with the government in matters of national defense.

"The opposition bloc should give us clear answers on what are the alternatives to stopping North Korea's nukes and missiles without the Terminal High Altitude Area Defense system and the Seoul-Washington alliance," Chung Jin-suk, the party whip said.

The lawmaker added the opposition parties' move to protest against the system deployment will hurt the critical alliance between South Korea and the United States.

"The claim that the issue can be solved through diplomatic channels is absurd," Chung also said.

Although the main opposition Minjoo Party of Korea remains neutral on the deployment, some of its lawmakers, as well as more left-leaning parties, have been expressing concerns over missile system, claiming such a move can hurt ties with China and Russia.

In line with the move, the minor People's Party also paid a visit to Seongju, 296 kilometers south of Seoul, where the THAAD system is slated to be deployed in 2017 on Monday.

There, the party claimed that the THAAD system will pave the way for a "permanent" separation of the two Koreas, adding that the government must scrap the plan and seek parliamentary approval.

Chung, meanwhile, added that other parties must remember the late President Roh Moo-hyun's efforts to send South Korean troops to Iraq, despite strong opposition from liberals, showed the critical nature of Seoul’s alliance with Washington. Roh is a symbolic figure for the opposition bloc even after his death in 2009. (Yonhap)