Elon Musk has reignited his long-simmering feud with Bill Gates — this time branding the Microsoft cofounder a “liar” amid growing controversy over U.S. foreign aid cuts and their potential global fallout.

Posting Sunday on X, Musk lashed out at Gates over warnings that funding reductions tied to the Trump administration could lead to widespread deaths overseas, particularly through cuts to United States Agency for International Development (USAID) programs, Benzinga reports.

Gates has publicly argued that reduced aid would devastate HIV treatment, vaccination efforts, and public health initiatives across Africa and other developing regions.

Musk wasn’t buying it.

“Bill Gates is pushing this lie, despite having over $80 billion dollars in his NGO that he could easily spend to save these alleged lives that are being lost,” Musk wrote. “Why doesn’t he? Bill Gates is a liar. Always has been.”

The blunt attack instantly went viral, adding fresh fuel to a clash between two of the world’s most powerful — and outspoken — billionaires.

Musk’s comments were directed at claims circulating online that deaths would directly result from the Trump administration’s move to slash U.S. funding to the United Nations through USAID.

The Gates Foundation did not immediately respond to requests for comment.

Gates, for his part, has repeatedly warned that cutting U.S. aid would have “devastating effects,” particularly in Africa, where global health programs rely heavily on American funding.

Gates has said the cuts could leave millions unvaccinated, disrupt HIV prevention efforts, and risk triggering a broader international health crisis.

But Musk argues that Gates’ warnings ring hollow given the massive resources controlled by Gates-backed organizations. In Musk’s telling, the billionaire philanthropist is exaggerating the threat while sitting on a fortune that could be deployed immediately.

The clash comes against the backdrop of Musk’s growing influence in government. Earlier this year, Musk’s Department of Government Efficiency (DOGE) spearheaded sweeping reductions to USAID, effectively gutting the agency. Musk previously declared that it was “time for it to die,” framing the cuts as part of a broader push to eliminate wasteful federal spending.

The war of words is just the latest chapter in a long-running rivalry. Musk has previously accused Gates of hypocrisy over climate change and famously blasted him for allegedly holding a short position against Tesla stock — a bet Musk claims Gates maintained “for ~8 years.”

As aid cuts ripple across the globe and Washington debates the future of foreign assistance, the very public Musk-Gates feud underscores a deeper divide among elites over power, responsibility, and who should foot the bill when governments pull back.

For now, one thing is certain: when Musk takes aim, he doesn’t miss quietly.