The spokesperson said the North's nuclear arms are a deterrence to protect the nation's right to existence and progress as an independent state against Washington's anti-North Korea policy.
European researchers say they have identified the targets North Korea is planning to attack.
U.S. President Donald Trump's decision to label the North as a "sponsor of terror" came nine years after George W. Bush, then the president, ordered removal of the North from the State Department's list of nations cited for egregious violations of norms of global behavior.
According to a report in The Financial Chronicle, Air China has suspended flights to North Korea, further limiting the secretive state's links with the outside world, in what the government said was a business decision with no political motives.
The order from the U.S. Treasury Department sanctioning a 13 Chinese and North Korean companies and agencies and 20 vessels owned by North Korea added substance to the words of Trump as he denounced North Korea for spreading terror at home and overseas.
New U.S. sanctions announced Tuesday against North Korea may add some substance to the symbolism, but only if China - which accounts for nearly all of North Korea's trade - decides to help. And, according to U.S. officials, some Chinese-based banks and trading firms continue to do business with the North in defiance of United Nations sanctions and USA threats of unilateral measures.
Terror designation a way to hike North Korea pressure
The United States has designated only three other countries - Iran, Sudan and Syria - as state sponsors of terrorism . Trump made the announcement one week after returning from a trip to South Korea , China, Vietnam and the Philippines.
Trump met China's President Xi Jinping earlier this month and is bullish about the US-China relationship, but concerns remain that Beijing is not ready to take tough measures against Kim.
The UN estimated the latest ban, imposed after its two intercontinental ballistic missile tests in July, would slash by North Korea's $3-billion annual export revenue by a third.
Trump warned that the terror designation and sanctions announcement would be part of a series of moves over the next two weeks to reinforce his "maximum pressure campaign" against Kim Jong-Un's regime.
The sanctions are on trade and labor contractors, including a North Korean company that has operated in China, Cambodia, Poland, and Russian Federation. China, moreover, still pours oil into North Korea, fueling an economy that otherwise survives on far less efficient coal. The spokesperson noted that their actions included expulsion of North Korean workers and diplomats.
Some North Korea analysts argue the state sponsor of terrorism designation and new sanctions could encourage a return to testing and belligerence from Pyongyang and discourage it from entering talks.
North Korea will re-join Iran, Sudan, and Syria who are in the USA list of state terrorism, as these countries "repeatedly provided support for acts of global terrorism".