A South Korean foreign ministry official said Friday that their government has seized a ship from Hong Kong, China, that is suspected to have engaged in mid-sea oil trade with North Korea in October, in violation of United Nation sanctions.

Earlier this week, images captured by U.S. satellites emerged online, which showed two vessels – one each from North Korea and China – carrying out some sort of a trade deal in a part of the West Sea, between China and South Korea.

The images were first made publicly available on Nov. 21, when the U.S. Department of the Treasury uploaded a report on their website, containing details of six North Korean shipping and trading companies and 20 of their ships sanctioned by the department on suspicion of carrying out illegal trade.

Surprisingly, President Donald Trump wrote in a tweet Thursday about how untrustworthy China has been for violating the sanctions placed on North Korea, giving off the impression that it was the first time that the POTUS had come to know of the illegal trades.

Furthermore, in an interview with New York Times on the same day, Trump confirmed he came to know about the incidents for the first time when he saw Fox News reporting it. As to why the president wasn’t informed of the Department of Treasury’s decision to sanction the North Korean ships — taken more than a month back — is anyone’s guess.

While the name of the North Korean ship — Ryesonggang 1 — was revealed by the Department of Treasury, the name of the Chinese ship was not revealed at the time.

The South Korean official told Reuters that the Chinese vessel is called Lighthouse Winmore.

The official added that the vessel transferred refined petroleum products to the North Korean ship in international waters. The U.S. has already proposed the blacklisting of Lighthouse Winmore, which had already been flagged by Hong Kong, for violating sanctions imposed upon North Korea over its growing nuclear weapons program.

The images in question were originally taken on Oct. 19, before the latest UN sanctions on North Korea on Dec.22, which limits oil product shipments to just 500,000 barrels a year, went into effect.

Regardless, North Korea was banned from engaging in any ship-to-ship trade with other countries since September.

“North Korea is known to employ deceptive shipping practices, including ship-to-ship transfers, a practice prohibited by United Nations Security Council Resolution (UNSCR) 2375 of September 11, 2017,” Department of Treasury’s report stated.

Earlier, South Korean media outlet Chosuilbo had quoted unnamed government officials of their country, who identified the vessels from China and North Korea.

“We need to focus on the fact that the illicit trade started after a U.N. Security Council resolution in September drastically capped North Korea's imports of refined petroleum products,” one South Korean government source said.

The officials also identified the location where the ships carried out the trade deal. It was in the part of the West Sea that is closer to the Chinese coast than South Korea.