The Korean Peninsula is on edge due to the crisis caused by North Korea’s nuclear and missile threats and the consequent standoff between the North and the US. As President Moon Jae-in said, it is the gravest crisis since the Korean War.

However, politicians in South Korea remain as divided as ever. They are obsessed with partisan fights, even though the nation is facing a crisis that raises the possibility of a military conflict on the peninsula.

There is already a long list of domestic issues that pit the ruling party against the opposition including the Moon administration’s unilateral decision to radically reduce dependence on nuclear-powered electricity; its attempt to replace public broadcasting executives appointed by the previous government; and its proposal to establish a new investigation agency that will deal exclusively with corruption and other crimes involving senior officials.

There is a more explosive issue: the alleged illicit political activities of the National Intelligence Service during the past conservative governments led by former Presidents Lee Myung-bak and Park Geun-hye. Some of the ministries have also opened investigations into major policy decisions made by the conservative governments, including the one on publishing state-authored history textbooks and the 2015 agreement with Japan on the issue of military sex slavery.

Some of the cases -- such as suspicions about the spy agency’s covert cyber operation aimed to strengthen and extend conservative rule, and the blacklisting of cultural figures and media professionals with liberal stances or critical views of the government -- are closing in on former President Lee, who stepped down in 2013.

Indeed, there are so many cases apparently targeting Lee that the former leader’s aides are calling them a politically motivated witch hunt.

Rival parties’ accusations against one another over what happened in the past drew additional heat from a controversy sparked by an opposition lawmaker.

Accusing the Moon administration of conducting a political vendetta against Lee over the death of former President Roh Moo-hyun, Rep. Chung Jin-suk of the Liberty Korea Party claimed Roh committed suicide in the wake of a domestic fight with his wife over a bribery scandal involving her and their son. Chung was arguing that it was wrong to believe Lee was behind the corruption probe on Roh.

The comments Chung made on Facebook invited strong backlash from the ruling party and Roh’s family members. Roh’s son filed a defamation suit against Chung.

All these political fights over things in the past come amid escalating tension between the US and North Korea. US bombers recently flew in the international airspace over waters east of the North -- the first flight of its kind since the end of the Korean War in 1953 -- and now the North is threatening to strike them down.

More worrisome is that the political community is divided over some of the key issues directly related to the North Korea crisis, including the proposal to redeploy US tactical nuclear weapons to counter threats from the North and the Moon administration’s decision to set aside $8 million in humanitarian aid to North Korea.

Granted, political parties are allowed to have different positions on political issues. But it is sad to see the ruling camp and the opposition engage in their usual fights instead of trying to form a united front to protect the nation from threats it has never faced before.