North Korea's diplomat for US affairs said that the US had "crossed the red line" by putting leader Kim Jong Un on its sanction list for alleged human rights abuses documented by the United Nations Human Rights Commission. The country said that it is now at war with the US, and might retaliate if the US and South Korea hold annual military exercise scheduled for next month.

"The Obama administration went so far to have the impudence to challenge the supreme dignity of the DPRK [Democratic People's Republic of Korea] in order to get rid of its unfavorable position during the political and military showdown with the DPRK," Han Song Ryol, director-general of the U.S. affairs department at the North's Foreign Ministry, told Associated Press.

"The United States has crossed the red line in our showdown," he added. "We regard this thrice-cursed crime as a declaration of war."

The US and South Korea conduct joint military exercises every year, and Pyongyang is never pleased with the drills.

North Korea had been heavily sanctioned in the past for its nuclear weapons program, but this month the US sanctioned the leader personally, essentially putting the two countries on a "war law," according to Pyongyang.

The human rights abuses listed against Kim relate to the prison camps in the country, and the US restrictions are directed to hold accountable those who are in a position to stop the state-sanctioned crimes.

North Korea persecutes all dissidents severely, but "reserves its most severe persecution for Christians," according to an annual 2016 report by the U.S. Commission on International Religious Freedoms (USCIRF).

Recently, North Korea banned import of all products that look like or have markings resembling the Christian cross.

"We've always had to make sure there were no Korean characters on the labels of products that we brought in from China," a source told Radio Free Asia. "Now we have to check again to see that there isn't anything that looks like a cross," he said.

"Some designs on women's clothing can look a lot like a cross, depending on who is looking at it. Cross designs also appear on women's hairpins and hair bands and on men's neckties."

The source told RFA that sometimes Chinese confectioneries are shaped like an 'X,' and its visual interpretations is at the discretion of the officials.

"If customs officers confiscate these products, insisting the shape looks like a cross, we have nowhere to complain," he added.

North Korea disconnected the last official communication line with the US a week after the sanctions were imposed.