San Francisco, California - Elon Musk sent out a memo to Twitter employees on Tuesday, demanding they work longer and harder – or leave the company.

According to CNN, the memo sent by the billionaire, with the subject line A Fork in the Road, gave employees an ultimatum.

"Going forward, to build a breakthrough Twitter 2.0 and succeed in an increasingly competitive world, we will need to be extremely hardcore," Musk wrote. "This will mean working long hours at high intensity."

"Only exceptional performance will constitute a passing grade," he added.

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He continues by sharing that Twitter will be "much more engineering-driven" and that "those writing great code will constitute the majority of our team and have the greatest sway."

Musk included a link to a form, which employees were expected to click, "If you are sure that you want to be part of the new Twitter." They have until Thursday afternoon to respond, or else they will be terminated and given three months of severance pay.

Elon Musk has made sweeping and chaotic changes since he acquired Twitter for $44 billion back in October, including firing top executives at the company and laying off nearly half its work force.