NVIDIA has ordered 300,000 more H20 AI GPUs from TSMC just weeks after the ban on selling to China was reversed. That's great news for NVIDIA, but some national security experts are sounding the alarm.

Demand in China has begun surging for a business that, in theory, shouldn't exist: the repair of advanced Nvidia artificial intelligence chipsets that the U.S. has banned the export of to its trade and tech rival.

Nvidia stock was rising Tuesday with sales of its artificial-intelligence processors seemingly poised to surge in China. The chip maker’s shares were up 1.2% at $178.84 in early trading. The stock rose 1.9% on Monday, marking another record close.