Microsoft said Tuesday that its new Windows 10 China Government Edition is ready for Chinese government agencies to use.

China Customs, the city of Shanghai, and China government-controlled IT company Westone Information Technology are Microsoft’s first customers for the new software. A Microsoft spokesperson said that this is the first time Microsoft has built a custom version of Windows for China.

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Microsoft’s (MSFT) debut of a tweaked version of Windows for China highlights the headaches involved when U.S. technology companies do business in that country. For example, an upcoming Chinese cyber security bill would require foreign technology companies to share with government inspectors the underlying software code of their products. The Chinese government claims that it needs to see the software code, which is usually proprietary, in order to verify that there are no flaws that hackers can exploit. Microsoft, along with IBM (IBM) and Intel (INTC), criticized the bill in December, according to the Wall Street Journal.

“Sharing source code in itself can’t prove the capability to be secure and controllable,” Microsoft said at the time. “It only proves there is source code.”

Part of the reason the Chinese government wants to scan the source code of foreign companies stems from the high-profile government leaks by whistleblower Edward Snowden. Some of Snowden’s leaks revealed that U.S. spy agencies were covertly installing so-called back doors in U.S.-based tech products like Cisco’s networking routers and switches that allowed them to carry out cyber espionage.

To address China’s concerns, Microsoft said in September that it would open a transparency center in Beijing where Chinese government officials could analyze various Microsoft products for security bugs.

Terry Myerson, a Microsoft executive vice president of Windows and devices, said in a blog post that for the past two years Microsoft has “has earnestly cooperated with the Chinese government on the security review of Windows 10.” Myerson said the new China version of Windows is based on the traditional Windows 10 Enterprise Edition for business customers but with extra features tailored to suit Chinese officials.

For example, Chinese government officials can use their own encryption technology in their version of Windows 10 to scramble data that they don’t want others to see. Additionally, the China version of Windows does not allow access to Microsoft’s OneDrive service, which lets people store documents and files on Microsoft-controlled data centers in what’s known as cloud-based storage.

Presumably, Chinese officials want to keep all of their data locked down on their own computers to minimize the risk of that information being stored to data centers that are outside their control.

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Microsoft also said that PC maker Lenovo is the company’s first partner that would pre-install the Chinese version of Windows on computers sold to Chinese government officials.