170209-N-GD109-083 
PACIFIC OCEAN (Feb. 9, 2017) Two E-2C Hawkeye early warning and control aircraft assigned to the "Black Eagles" of Carrier Airborne Early Warning Squadron (VAW) 113 fly over the aircraft carrier USS Carl Vinson (CVN 70) during a change of command ceremony. The ship's carrier strike group is on a western Pacific deployment as part of the U.S. Pacific Fleet-led initiative to extend the command and control functions of U.S. 3rd Fleet. (U.S. Navy photo by Mass Communication Specialist 2nd Class Zackary Alan Landers/Released)
PHOTO: Spec. 2nd Class Zackary Alan Landers//U.S. Navy
170209-N-GD109-083 PACIFIC OCEAN (Feb. 9, 2017) Two E-2C Hawkeye early warning and control aircraft assigned to the "Black Eagles" of Carrier Airborne Early Warning Squadron (VAW) 113 fly over the aircraft carrier USS Carl Vinson (CVN 70) during a change of command ceremony. The ship's carrier strike group is on a western Pacific deployment as part of the U.S. Pacific Fleet-led initiative to extend the command and control functions of U.S. 3rd Fleet. (U.S. Navy photo by Mass Communication Specialist 2nd Class Zackary Alan Landers/Released)
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SINGAPORE - JUNE 12: In this handout photo, North Korean leader Kim Jong-un shakes hands with U.S. President Donald Trump during their historic U.S.-DPRK summit at the Capella Hotel on Sentosa island on June 12, 2018 in Singapore. U.S. President Trump and North Korean leader Kim Jong-un held the historic meeting between leaders of both countries on Tuesday morning in Singapore, carrying hopes to end decades of hostility and the threat of North Korea's nuclear program. (Photo by Kevin Lim/THE STRAITS TIMES/Handout/Getty Images)
PHOTO: Handout/Getty Images AsiaPac/Getty Images
SINGAPORE - JUNE 12: In this handout photo, North Korean leader Kim Jong-un shakes hands with U.S. President Donald Trump during their historic U.S.-DPRK summit at the Capella Hotel on Sentosa island on June 12, 2018 in Singapore. U.S. President Trump and North Korean leader Kim Jong-un held the historic meeting between leaders of both countries on Tuesday morning in Singapore, carrying hopes to end decades of hostility and the threat of North Korea's nuclear program. (Photo by Kevin Lim/THE STRAITS TIMES/Handout/Getty Images)
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WASHINGTON, DC - MAY 09:  National Security Adviser John Bolton speaks on a morning television show from the grounds of the White House, on May 9, 2018 in Washington, DC. Yesterday President Donald Trump announced that America was withdrawing from the Iran nuclear deal.  (Photo by Mark Wilson/Getty Images)
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WASHINGTON, DC - MAY 09: National Security Adviser John Bolton speaks on a morning television show from the grounds of the White House, on May 9, 2018 in Washington, DC. Yesterday President Donald Trump announced that America was withdrawing from the Iran nuclear deal. (Photo by Mark Wilson/Getty Images)
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Story highlights

Trump praised China for refusing N. Korean coal this week, saying it was a "big step"

A spokesman for Chinese Customs said all coal imports were banned from February 18

(CNN) —  

US President Donald Trump says China has turned a fleet of coal-carrying cargo ships back to North Korea this week, describing it as a “big step” towards cracking down on the rogue state.

China banned all imports of coal from North Korea in mid-February, soon after Pyongyang tested a new intermediate-range missile.

Almost all coal shipments to the Chinese city of Dandong, on the North Korean border, since February have been turned back, a source with knowledge of North Korean government operations in Dandong told CNN.

The ban followed strict, new sanctions imposed in November by the United Nations on North Korean coal exports, which China helped to draft and pass

02:35 - Source: CNN
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North Korean delegates arrived in Seoul on January 21 on their way to inspect venues and prepare cultural performances for next month's Winter Olympics, in the first visit by Pyongyang officials to the South for four years. / AFP PHOTO / KOREA POOL / - / South Korea OUT        (Photo credit should read -/AFP/Getty Images)
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Hyon Song-Wol (C), the leader of North Korea's popular Moranbong band, arrives at Seoul station in Seoul on January 21, 2018 before boarding a train bound for the eastern city of Gangneung. North Korean delegates arrived in Seoul on January 21 on their way to inspect venues and prepare cultural performances for next month's Winter Olympics, in the first visit by Pyongyang officials to the South for four years. / AFP PHOTO / KOREA POOL / - / South Korea OUT (Photo credit should read -/AFP/Getty Images)
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Coal accounted for a third of all official North Korean exports in 2015, making up a large part of its income. China is by far North Korea’s largest trading partner.