At dawn on Thursday morning, the quiet as we set up for our News At Ten live was broken by the sound of a train coming across the Friendship bridge from North Korea and into China.
As it came closer we could see that it appeared to be a coal train.
We knew that if that was indeed the case, this would be a breach of the coal trade embargo China had imposed in February this year - its toughest sanction yet on it’s so-called ally.
We showed our footage to experts and they immediately identified it was Anthracite, a high quality coal used primarily in the steel industry.
A recent report from experienced North Korea watchers 38 North, showed that following the implementation of the ban it would be the lack of Anthracite that would hit China hardest.
Colleagues in Beijing presented what we had seen to the Ministry of Foreign Affairs and their response was to insist China has “consistently, accurately and strictly implemented all the UNSC resolutions in their entirety".
We cannot prove what was in the carriages of that train, we cannot confirm their destination.
All we can state is that in the early hours of Thursday morning we saw a coal train coming across from North Korea into China.
The train was not turned back by those manning the checkpoint as it would have been easy to do.
This comes following reports last week that cargo ships carrying coal had docked in the Chinese Port of Tangshan.
In response the Ministry of Foreign Affairs insisted China had stopped importing coal from its secretive neighbour.
“China has stopped this year's import of coal produced in the DPRK as a way to strictly observe our obligations as a UN member state and implement Security Council resolutions," a spokesperson said.
"I can assure you that China has been strictly implementing them.
"As for some later reports claiming that vessels might dock at Chinese ports, the thing is that if these vessels continue sailing on sea or drifting outside the ports, the crew members will encounter difficulties that warrant our humanitarian help.”
The Ministry of Foreign Affairs did admit that some North Korean coal had unloaded in China but “that does not mean it has been imported".
If China has flouted it’s own ban it would never admit doing so and traders we have spoken to in Dandong tell us that the coal trade has died off.
Beijing has an unwritten rule to protect it’s neighbour.
It has gone further than ever before with its economic sanctions but it’s proving hard to determine just how strictly they are being enforced.