Microsoft Corp. President Brad Smith wrote to Ukraine's leader this month with a clear message: Despite Kyiv's calls for it to sever all ties with Russia, the U.S. software behemoth would continue doing business in the country with nonsanctioned clients, including schools and hospitals.

"Depriving these institutions of software updates and services could put at risk the health and safety of innocent civilians, including children and the elderly," Smith said in the previously unreported March 14 letter.

Smith told Ukrainian President Volodymyr Zelenskyy that Microsoft was "mindful of the moral responsibility" to protect civilians. However, he said the company was discussing with U.S., British and EU governments whether "to halt any ongoing services and support" in Russia and would move "in lockstep with their sanctions and other economic goals."