Recently, the MacArthur Foundation announced that it was withdrawing from nuclear security grantmaking, creating a potentially large shortfall in philanthropic funding in the coming years (https://www.politico.com/news/2021/07/19/washington-arms-controllers-nuclear-weapons-500126). 

Other funders, like Longview Philanthropy, have stepped in (https://forum.effectivealtruism.org/posts/M7wNHbpqnLfDzmDK9/new-nuclear-security-grantmaking-programme-at-longview), but there is still an expected funding shortfall of over $5 million by some estimates.

This question resolves if a single new funder (or a group of funders under one umbrella organization) announces that it will commit at least $5 million (in addition to what they currently give) a year to nuclear security by the end of 2023.