Seoul (CNN) North Korean officials have returned to a joint liaison office near the demilitarized zone (DMZ) with South Korea, days after they informed Seoul they would be withdrawing from the project, a key symbol of the rapprochement and ongoing peace process between the two countries.

"It was announced today by the US Treasury that additional large scale Sanctions would be added to those already existing Sanctions on North Korea. I have today ordered the withdrawal of those additional Sanctions!" Trump tweeted on Friday.

While Trump's tweet came after sanctions imposed against Chinese shipping companies which did business with Pyongyang, two sources familiar with Trump's tweet told CNN it was in fact not about those sanctions, but instead about additional large-scale sanctions targeting North Korea that have been in the works.

While Pyongyang had not mentioned the sanctions in its communication to Seoul about withdrawing from the liaison office, analysts pointed to the apparent worsening relationship with Washington following a failed summit between Trump and North Korean leader Kim in Hanoi last month as the likely cause of the move.

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