Huawei’s newest smartphone has been spotted with memory chips from South Korea’s SK Hynix, despite US sanctions designed to stop such components from reaching the Chinese company.

The new Mate 60 Pro is grabbing headlines for underscoring Huawei’s ability to develop a smartphone that's seemingly based entirely on Chinese tech — circumventing any reliance on foreign chip supplies. This includes using a 7-nanometer processor from Chinese chip maker SMIC, putting it on par with iPhones released in 2018.

But according to Bloomberg, a sample Mate 60 Pro that was torn down by Canadian firm TechInsights also showed the product contained SK Hynix’s LPDDR5 and NAND flash memory.

The SK Hynix components represent an “isolated example of materials sourced from overseas,” TechInsights told Bloomberg. Still, the use of the memory chips is raising questions over whether US sanctions have been effective at stopping Huawei from sourcing foreign technology.

In response, SK Hynix has been telling Korean publications it’s opened an investigation into how its memory chips ended up in the phone. “SK Hynix no longer does business with Huawei since the introduction of the US restrictions against the company,” the vendor told The Korea Times.

“Also, SK Hynix is strictly abiding by the US government's export restrictions,” the company said, noting it had also reported the matter to the Bureau of Industry and Security under the US Commerce Department, which oversees export controls.

In the meantime, the Mate 60 Pro is also sparking questions over whether US sanctions have backfired by forcing China to build up its own chip-manufacturing technology. Or if the US needs to tighten the sanctions even more. For now, the White House has only said it wants to first obtain more details about the Huawei phone and its internal chip before commenting any further.

Huawei didn’t immediately respond to a request for comment.