Microsoft co-founder Bill Gates has some advice for today’s top tech giants with regard to dealing with the government.

In a recent phone interview with Axios, Gates said modern tech titans “need to be careful that they're not ... advocating things that would prevent government from being able to, under appropriate review, perform the type of functions that we've come to count on.”

When asked if he sees signs of that now, he replied, “Oh, absolutely.”

Pressed on the matter, Gates pointed to some companies’ “enthusiasm about making financial transactions anonymous and invisible, and their view that even a clear mass-murdering criminal's communication should never be available to the government.”

That last bit is a clear jab at Apple and its handling of an iPhone belonging to Syed Rizwan Farook, one of the San Bernardino shooters. When asked by Axios if he was referring to that incident, Gates said, “There’s no question of ability; it’s the question of willingness.” In other words, it sounds as if Gates doesn’t buy Apple CEO Tim Cook’s claim that they don’t have a backdoor to the iPhone (and that creating one would be considered too dangerous).

While on the horn, Gates also questioned the level at which technology is empowering small groups of people to cause damage. “[I]t's easier for kids to do genetics in a laboratory. That's a really good thing, unless a few people decide to make human-transmissible smallpox and spread that into the world.”

“A small group can have an impact — in the case of nuclear, on millions; and in the case of bio, on billions. That is scary to me.”

Gates’ interview was published ahead of the arrival of the annual letter from the Bill & Melinda Gates Foundation. In their 10th annual letter, the two discuss 10 tough questions that people often ask them with topics touching on President Trump’s policies, overpopulation, education and more.