Pegatron, a Taiwanese company that is one of a few companies that assemble the iPhone, has halted production at two plants in Shanghai and one in Kunshan to comply with the Chinese government’s stringent COVID-19 regulations, according to Nikkei Asia. China has put strict policies in place in response to a recent resurgence of COVID-19 in the country.

The shutdown could have a significant impact on both Pegatron and Apple. Nikkei Asia reports that those Pegatron plants are its only iPhone manufacturing hubs, and Pegatron is responsible for making “roughly” 20 to 30 percent of all iPhones. Pegatron “hopes to resume production soon,” the publication said, though it’s unclear exactly when that might happen.

Apple didn’t immediately reply to a request for comment. Quanta, which helps make MacBooks, has also halted production at a site in Shanghai, according to Nikkei Asia.

Supply chain issues have been a consistent problem during the pandemic, affecting companies across many industries. Tesla also had to close its Shanghai factory in response to China’s restrictions, for example. And the global chip shortage has made it more difficult to buy all sorts of consumer electronics.