President Donald Trump’s reelection campaign has filed a libel lawsuit against The New York Times over an opinion article published last year about Trump’s dealings with Russia. The opinion article makes the case that Russia and Trump’s 2016 campaign team established a warm relationship to get mutual benefits, with the Russians offering to help undermine Hillary Clinton’s candidacy, while the Trump team offered ideas to relieve sanctions imposed by President Barack Obama.

“The Trump Campaign has turned to the courts to try to punish an opinion writer for having an opinion they find unacceptable,” The New York Times said in a statement provided to The Verge. “Fortunately, the law protects the right of Americans to express their judgments and conclusions, especially about events of public importance. We look forward to vindicating that right in this case.”

The lawsuit particularly seizes on the phrase “quid pro quo,” which is often taken as a specific exchange between Trump campaign and the Russian government. Special counsel Robert Mueller’s report failed to find definitive evidence of such an exchange, but the Times op-ed argues that such evidence is not necessary, painting the mutually beneficial relationship itself as a “quid pro quo.”

Still, the use of the term seems to have enraged the Trump campaign. It is a common term for the president; Trump has tweeted about it 19 times since October 2019. All but two of those tweets are in defense of a July 2019 call with Ukrainian president Volodymyr Zelensky, in which Trump and his aides allegedly tried to coerce the government of Ukraine into announcing an investigation of former Vice President Joe Biden.

During the 2016 campaign, WikiLeaks published many internal emails with damaging information from the Democratic National Committee. Those emails were believed to have been stolen and leaked by Russian intelligence officers. And Russia is already meddling in the 2020 presidential election to help Trump, according to a briefing given to the House Intelligence Committee earlier this month. The New York Times and The Washington Post reported on that briefing.

The Trump campaign has not yet replied to a request for comment.

Here is the full filing: