The administration holds in reserve a list of Chinese banks and other firms the Treasury Department has been preparing to sanction for their alleged ties to North Korea's military programs."Right now, our focus is on carrying out the existing sanctions and ensuring compliance with the new U.N. Security Council resolution", a senior White House official told Reuters on Tuesday, adding there was "nothing imminent to announce" on secondary sanctions. The bill places draconian limits on North Korea's exports of coal, lead, iron, lead ore, iron ore, and seafood.
Though Beijing repeated its call for the United States and North Korea to resume talks, the USA said that was still premature, and rejected yet again a Chinese call for the U.S.to freeze joint military exercises with South Korea in exchange for the North halting nuclear development.
Tillerson is in Manila for a meeting of the 10-nation ASEAN regional bloc, but all eyes will be on his one-on-one talks with his counterparts from Washington's great power rivals, Russian Federation and China.
North Korea argues that its nuclear and missile programs are only aimed at deterring an eventual invasion from the USA, a country with which the regime has been technically at war for more than 60 years.
Last week, Mr Tillerson said North Korea needed to cease both its missile launches and nuclear weapons tests for talks to begin.
Joint discussions between six nations - China, Japan, North Korea, South Korea, Russia and the US - collapsed in 2009. "We must be tough & decisive!" he wrote.
China, North Korea's lone major ally, has repeatedly said it is committed to enforcing increasingly tough United Nations resolutions on North Korea, though it has also said what it terms "normal" trade and ordinary North Koreans should not be affected.
When CBS News visited North Korea in the spring, we watched as Kim unveil a massive new neighborhood of shimmering high rises; his way of showing the world that six previous rounds of United Nations sanctions over more than a decade have not worked.More news: Mosquitoes carrying West Nile Virus found in Regina
"North Korea should realise if it doesn't stop its nuclear, missile provocations, it will face even stronger pressure and sanctions", Defence Ministry spokesman Moon Sang-gyun told a regular news briefing. "Even allies in the region like China, Japan, South Korea, all agreeing with the United States that North Korea and its nuclear capabilities must be stopped".
The Trump administration has made North Korea a top priority, with Tillerson announcing an global pressure campaign in April that U.S. officials and observers say is beginning to tighten the noose on Pyongyang. It also prohibits countries from increasing the number of North Koreans working overseas and bans new joint ventures with the North as well as any new investment in current joint ventures.
North Korean Foreign Minister Ri Yong Ho, left, is greeted by his Chinese counterpart Wang Yi prior to their bilateral meeting in the sidelines of the 50th ASEAN Foreign Ministers' Meeting and its Dialogue Partners Sunday, Aug. 6, 2017 in Pasay city, Manila. Instead, the US was represented at the dinner by Thornton, whose official title is acting assistant secretary of State for East Asia and Pacific Affairs.
"The North Koreans contend that they can not relinquish their nuclear program until the U.S. ends its hostile policies", she said.
The United States has remained technically at war with North Korea since the 1950-53 Korean conflict ended in an armistice rather than a peace treaty.
Tillerson's remarks might be an attempt to try another tack by the United States, which also has tried to get Pyongyang's ally China to use its influence to prevent North Korean leader Kim Jong Un from building a nuclear arsenal.
The North Korean response was typically robust, threatening to teach the U.S. "a severe lesson" if it sought to punish the North for its nuclear ambitions.
Jay Lefkowitz, a former US special envoy on human rights in North Korea, said China's efforts were encouraging but he questioned the value. "But North Korea has been able to evade sanctions in the past, and it's not clear to me things are going to be much different this time".