According to a report by Reuters, citing Chinese oil executives on the matter
For some background, China is Iran's biggest oil customer and it looks like that is not going to change in the near-term as US sanctions start nearing. Chinese oil companies are starting to shift their cargoes from their own vessels to those owned by National Iranian Tanker Co ("NITC") to keep the oil supply flowing, according to a Reuters report.
It is said that in June, 8 of 19 vessels were still operated by the Chinese but in July, all 19 vessels delivering oil from Iran to China were operated by the NITC already. According to the oil executives spoken to, the move is to safeguard their supplies and that means Iran will now have to cover all costs and risks of delivering the oil supply - including insurance (not sure how they are going to go about this, but yeah).
The idea here is to circumvent the sanctions applied by the US on companies dealing with Iran so instead NITC will have to shoulder more responsibility in order to keep the "business dealings" going. I reckon this means that NITC will be shipping the oil to Chinese shores but its customers' information will be safeguarded in that respect. It is the same thing that happened in the past before the sanctions on Iran were lifted in 2016.
