When Huawei announced its latest smartphone last week, the world’s largest telecommunications gear maker also shared another product. Track AI promises to pair software with Huawei devices to let “non-trained professionals” diagnose eye conditions.

Missing from the Chinese company’s announcement was Google’s work behind the scenes.

Huawei Technologies Co. built Track AI using TensorFlow, a set of AI software tools from Alphabet Inc.’s Google. TensorFlow is also open-source, so anyone, anywhere can use it and Google can’t control access.

However, a creative team that works with Google’s advertising clients also provided marketing help to Huawei, according to Google spokesman Chris Brummitt. These teams regularly work with Google clients to “make the most of what’s possible with technology, leading to ideas like this one,” Brummitt added, while stressing that no Google engineers worked on the project. A Huawei spokesman confirmed the partnership.

The Track AI initiative is not a major strategic priority for either of the technology giants but it does underscore the important business relationships that Google has been trying to build with Chinese companies like Huawei for decades.

Artificial intelligence is a major investment area for both companies, and health-care diagnostics is one of the ripest fields for image-recognition software. Yet the collaboration happened during a particularly fraught moment. Huawei is a pariah for the Trump Administration amid concerns it could pose a threat to national security and be a vehicle for Beijing’s spying, allegations the company has consistently denied. Google’s AI efforts in China are the subject of scathing criticism from the U.S. military.

Google’s support for Track AI may be tied to the U.S. company’s huge advertising business, which caters to Chinese companies looking to reach customers outside the country even as its search business remains blocked on the mainland. While Google doesn’t disclose how much revenue it generates in China, Asia accounted for about 15 percent of revenue last year.

Huawei and Google have also worked closely in the past. The Shenzhen-based company’s phones use Google’s Android software and, outside of China, rely heavily on the U.S. firm’s apps including search, Chrome and Maps. In 2015, the Chinese manufacturer designed a model of the Nexus smartphones, which Google co-marketed.

Last June, the corporate friendship fell under political fire. Five U.S. Senators wrote a letter to Google Chief Executive Officer Sundar Pichai saying the company’s partnership with Huawei “could pose a serious risk to U.S. national security and American consumers.”

Pichai met last week with a top military official and President Donald Trump, who have both criticized the tech giant for its work in China.

Politics have done little to dent Huawei’s growth. Last week, the company posted a 25 percent jump in annual profit despite concern about the security of its telecommunications network products.