Sean Penn has delivered an ultimatum that could have a wide-ranging impact on Hollywood as the Delta variant of COVID-19 rages in Los Angeles, causing mask mandates to be reinstated and restaurants to close once again.

After returning from the Cannes premiere of his movie “Flag Day”, Penn was to have returned to work on Starz series “Gaslit”, in which he’s starring alongside Julia Roberts.

However, Deadline is reporting that Penn has “drawn a line in the sand,” insisting that everyone in the production has been vaccinated for the virus before he’ll return to set; he’s even offered to provide free vaccinations to unvaccinated cast and crew through his organization, CORE.

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As Deadline points out, Penn’s move is intended to send a message, “based on the principle that to go unvaccinated puts everyone around you in jeopardy on a set,” challenging a recent agreement between Hollywood leaders to go further and make vaccination mandatory; while vaccination is “considered a personal choice,” it’s no secret that experts are pinning the recent spike in COVID cases to those who are refusing to get vaxxed.

The issue of making vaccinations mandatory is legally thorny, and puts the studio in a difficult position — which, Deadline explains, is apparently the point.