Microsoft is eliminating 18,000 jobs over the next year as it works to integrate the Nokia handset business it acquired in April, CEO Satya Nadella announced on Thursday.

About 12,500 of the reductions are expected to come from Nokia, including professional and factory workers.

In a memo to employees, Nadella also said Microsoft will largely nix work on Android-based devices. "We plan to shift select Nokia X product designs to become Lumia products running Windows," he wrote. "This builds on our success in the affordable smartphone space and aligns with our focus on Windows Universal Apps."

In a separate email to employees, Microsoft exec - and former Nokia chief - Stephen Elop said "we expect to make this shift immediately while continuing to sell and support existing Nokia X products."

"Whereas the hardware business of phones within Nokia was an end unto itself, within Microsoft all our devices are intended to embody the finest of Microsoft's digital work and digital life experiences, while accruing value to Microsoft's overall strategy," Elop said. "Our device strategy must reflect Microsoft's strategy and must be accomplished within an appropriate financial envelope. Therefore, we plan to make some changes."

And change it will. "We are moving now to start reducing the first 13,000 positions, and the vast majority of employees whose jobs will be eliminated will be notified over the next six months," Nadella wrote. "My promise to you is that we will go through this process in the most thoughtful and transparent way possible. We will offer severance to all employees impacted by these changes, as well as job transition help in many locations, and everyone can expect to be treated with the respect they deserve for their contributions to this company."

The cuts come less than three months after Microsoft completed its $7.2 billion acquisition of Nokia's smartphone and mobile phone businesses. Following the Nokia deal, Microsoft's employee headcount rose from about 99,000 last year to 127,000 as of last month, according to the Associated Press.

Nadella last week first hinted that layoffs might be on the horizon. "Organizations will change. Mergers and acquisitions will occur. Job responsibilities will evolve. New partnerships will be formed. Tired traditions will be questioned," Nadella wrote in a lengthy memo to staffers.

This round of layoffs eclipses the 5,800 cuts made five years ago — the largest in Redmond's history. Microsoft has handed out a number of pink slips since then, dropping an undisclosed number of marketing and advertising jobs two years ago.

The Nokia X, meanwhile, made its debut at Mobile World Congress in February, and the follow-up X2 (pictured) was revealed just last month. The devices are not the Android many have come to expect, though. Nokia built the Nokia X Software Platform 2.0 from the Android Open Source Platform (AOSP), making it a mix between Nokia's Asha line and low-end Windows Phone line, mimicking the tile-based look of the latter, but integrating some of the user-friendly features from the former.

For more, check out How the Nokia X2 and Moto X+1 Mislead You. Also see Microsoft's Nokia Deal: What it Means and Winners and Losers From Microsoft's Nokia Acquisition.