The ongoing tension between Tesla Inc. (TSLA) CEO Elon Musk and Microsoft Corp (MSFT) cofounder Bill Gates just got more heated. Musk took to X on Sunday to directly call Gates a liar over the controversy surrounding foreign aid cuts.

The Public Callout

Musk's criticism came in response to posts discussing claims about deaths potentially resulting from President Donald Trump's announcement of funding cuts to the United Nations via the United States Agency for International Development (USAID). According to Musk, Gates was "pushing this lie, despite having over $80 billion dollars in his NGO."

The Tesla CEO suggested Gates could "easily spend to save these alleged lives that are being lost" if the situation were truly as dire as described. Then came the direct shot: Gates is "a liar," Musk declared.

The Gates Foundation didn't immediately respond to requests for comment.

The Context Behind the Clash

Gates has been vocal about what he sees as devastating consequences from these funding decisions. He's warned specifically about HIV programs in Africa facing severe impacts, and raised alarms that millions could go unvaccinated, potentially triggering a global health crisis.

The aid cuts trace back to Musk's Department of Government Efficiency (DOGE), which effectively shut down USAID through massive funding reductions. Back in February, the Tesla and SpaceX CEO declared it was "time for it to die."

This isn't the first time these two billionaires have butted heads. Musk has repeatedly called out Gates over an alleged short position against Tesla stock that Gates has supposedly held for roughly eight years.