Cheng Xiaohe, a North Korea expert at Renmin University of China in Beijing, said the US government did not have factual evidence these companies were violating sanctions.
U.S. secretary of state Rex Tillerson went out of his way on Tuesday to note that North Korea hadn't carried out "provocative acts" since the UN Security Council imposed new sanctions on the country, saying that restraint might lead to negotiations over its nuclear arsenal.
A KCNA report said: "Dear supreme leader said that the Americans' reckless military confrontational behavior has ended up the United States trapping themselves with their own hands and are spending pathetic fate by tired minutes and seconds and that dear supreme leader will watch such stupid American behaviour for a bit longer".
North Korea's envoy to a disarmament conference in Geneva reiterated this stance earlier on Tuesday. That suggested his intent was to give Kim Jong Un's regime an opening and a signal. Kim has pledged to develop a nuclear missile that could hit the U.S. mainland.
Pyongyang in response said that it would launch missiles into the waters near the US Pacific island of Guam, where American troops are stationed and some 160,000 US citizens live.
On Aug 6, the United Nations Security Council unanimously imposed new sanctions on North Korea banning exports of coal, iron, iron ore, lead, lead ore and seafood, in a bid to choke off a third of Pyongyang's US$3 billion in annual export revenue.
The U.N. sanctions were a response to twin tests last month of an intercontinental ballistic missile that may be able to reach parts of the USA, heightening concern in Washington that North Korea could soon be able to threaten it with nuclear weapons.
On Tuesday, the US Department of the Treasury's Office of Foreign Assets Control introduced new sanctions against 10 entities, including Chinese ones, for violating UN Security Council (UNSC) resolutions on North Korea.
Prosecutors in Washington are seeking to recover $11 million from companies based in China and Singapore that they accuse of conspiring with North Korea to evade sanctions. The suits allege that the two companies participated in schemes to launder US dollars on behalf of sanctioned North Korean entities.
Tillerson has repeatedly delivered stern messages to North Korea, saying in April, for example, that the two sides were nowhere near ready for negotiations. The Treasury claims the sanctions are in line with the internationally agreed measures against North Koreas missile and nuclear weapons programs.
He added, however: "We need to see more on their part". "I think it's important to take note of that".