If — and this may be the most critical “if” to occur in diplomacy for many years — North Korean dictator Kim Jong Un is serious about a proposal being discussed now, it could represent a true breakthrough.

While most attention during recent months has focused on North Korea’s nuclear weapons, it has a fearsome conventional arsenal, too. Kim’s forces have thousands of artillery pieces near the DMZ with South Korea. Most are pointed at that nation’s capital, Seoul.

Should Kim give the order to fire, it is likely hundreds of thousands of South Koreans and many Americans would die in the ensuing barrage.

Now, however, it is being reported officials from South Korea and North Korea are discussing removal of Pyongyang’s long-range artillery from the border area.

If that happens — and so many artillery pieces are involved that it could be verified — Kim would be giving up a major threat.

That could indicate seriousness about other steps in a more comprehensive disarmament process.

Whatever encouragement the United States can provide for such action should be given. Making South Koreans feel less threatened by Kim’s artillery would be a major breakthrough.