The U.S. government on Friday warned that a planned inter-Korean liaison office in the shuttered Kaesong Industrial Complex "could violate not only United Nations but U.S. sanctions against North Korea."

"If the [South] Korean government opens a liaison office in Kaesong, [South] Korea will risk violating sanctions that have drawn North Korea back to the negotiating table," a U.S. official told the Chosun Ilbo on condition of anonymity.

He added the liaison office could place the U.S. "in a difficult situation." In other words, it may have to take action against its ally if any sanctions are violated in the process of setting it up.

South Korea aims to supply the office with electricity, construction materials, equipment and other goods, and that could fall foul of the sanctions.

The official added that Washington is obligated to investigate suspicions and that punitive measures will ensue if violations are found. He insisted that sanctions against the North and regulations must be obeyed even to "advance diplomatic objectives."

The plan for the liaison office was agreed between President Moon Jae-in and North Korean leader Kim Jong-un at their April 27 summit. The South recently started refurbishing the liaison office in the border city and began supplying electricity, while preparations are under way for the opening ceremony.

Moon said last Wednesday, "In a few days, we will see the opening of an era in which the South and North communicate with each other 24 hours a day, 365 days a year."

But the scheduled opening on Friday fell through, and a Cheong Wa Dae official said no fresh date has been decided.

