And the president has continued to deride and seek to discredit mainstream news organizations, including CNN, The New York Times and Washington Post.
US officials investigating Russia's alleged attempt to interfere in the election are now looking into such adverts.
In a possible reaction to growing reports that Facebook sold pro-Trump advertisements to a Russian-linked internet research group during the 2016 election, President Donald Trump said the social media giant was "always anti-Trump".
Trump himself has previously praised Facebook and credited it with helping him win the November election. "Social media platforms, such as Twitter and Facebook, have the ability to serve as an effective propaganda arm conveying specific messages to geographically targeted audiences".
Politico reported the ad supporting Green Party candidate Stein came late in the campaign, among other ads from shadowy Russian sources that criticized Clinton and promoted Bernie Sanders, even after the Democratic primary campaign was over.
But he followed up his "anti-Trump" post by touting who he said is "Pro-Trump!" - the American people.
The company still does not know the extent of Russia's ad purchases or whether these unidentified ad buys are still on the site.
The committee, which oversees US scientific agencies, believes such anti-fracking ads reflect "the Russian government's concern about the impact of fracking. on the global energy market and potential challenges to profitability" of Russian energy companies, the letter said.
The advert that backed Stein, which did not specifically dismiss Clinton but put across the case for her opponent, read: "Choose peace and vote for Jill Stein". It is also suspected that these Russian actors had an impact on the results of the elections, and if not, then they had vast influence.