Elon Musk's life seems rather busy. He has a new girlfriend and a newborn with his ex-partner, musician Grimes.

When he is not dating or parenting, he is the world's richest man. So, the fact that he has time to tweet is surprising. In one of his latest tweets, he challenged the Russian president to a duel.

Musk used Cyrillic letters to name Putin and Ukraine.

This tweet came with a follow-up, where the founder of SpaceX wrote in Russian, "Do you agree to this fight?" and tagged the Russian president.

The Tesla CEO's tweet came as a surprise despite his open criticism and public mocking of the leader of Russia's space agency.

The Tesla CEO sent shipments of a satellite-based internet system to Ukraine to make Internet services reliable as the country's infrastructure is falling apart due to the bombing.

Though there was no public response from Kremlin, Ukrainian president Volodymyr Zelenskyy thanked Musk for the help and invited him over once the war was over.

Before this challenge, Musk tweeted a series of cryptic posts. He wrote:

"There is a beauty to the biological substrate."

The second said:

"By the pricking of my thumbs..."

The second is related to Shakespeare's Macbeth, The Independent reports, which initially says: "Something wicked this way comes."

Ukraine has been fighting Russian forces since February 24.