In April 2016, the Russians approached the Trump campaign through one of its few foreign-policy advisers, George Papadopoulos, someone Mr. Trump touted as an “excellent guy.” They informed Mr. Papadapoulos they had “dirt” on Hillary Clinton in the form of “thousands of emails,” emails which we now know the Russians had hacked from Democratic National Committee servers and campaign officials’ accounts.

Weeks later, in June, the Russians followed up with an approach to the highest levels of the campaign—the president’s son, son-in-law and campaign manager—once again offering dirt on Mrs. Clinton as part of what was described as the Russian government’s effort to help Mr. Trump. The campaign response back to the Kremlin through the meeting in Trump Tower was twofold: We would “love” the help, and we were bitterly disappointed with what you gave us. Given that Russian interlocutors had already informed Mr. Papadopoulos of their valuable cache of stolen emails, the campaign was on notice that the Russians had far better dirt to offer.

Days after the meeting in Trump Tower, Julian Assange of WikiLeaks announced receipt of the hacked DNC emails. The Russians also published stolen emails directly through their fictitious proxies, DC Leaks and Guccifer 2.0. At the same time, the Russians ramped up a massive social-media campaign using an extensive network of fake personas and accounts to help the Trump campaign, vilify Mrs. Clinton and sow general discord.

As the Russians pushed out the stolen materials, Mr. Trump and his surrogates touted the hacked emails on a daily basis. Mr. Trump even publicly urged the Russians to further hack and disseminate his opponent’s emails.