The whistleblower expresses confusion about Trump’s references to CrowdStrike during his calls with Ukraine President Volodymyr Zelensky.

Some context: The Democratic National Committee hired CrowdStrike in 2016 to investigate hacks to its computers, which were later blamed on the Russian government.

In the call, Trump mentioned the US cybersecurity firm and said, “the server, they say Ukraine has it.” Trump also encouraged Zelensky to “find out what happened” with the server.

“I do not know why the President associates these servers with Ukraine,” the whistleblower wrote in a footnote in their letter, which was addressed to Congress.

The whistleblower added that Trump had previously connected the DNC server to Ukraine in television interviews.

Trump’s interest in CrowdStrike and the DNC server, more than three years after the hacks, is part of a larger effort to undermine the notion that Russia meddled in the 2016 election to help him win. He has repeatedly rejected the assessment from CrowdStrike, which was later confirmed by US intelligence agencies, that Russia was behind the DNC hacks and leaks.