As evidence mounts that Russian President Vladimir Putin's government intervened in the American presidential election, allegedly taking deliberate steps to help elect Donald Trump, it's easy to forget that this story has unfolded slowly, piece by piece, over the course of about a year.With that in mind, let's take a stroll down memory lane.September 30, 2015: Trump, the then-frontrunner for the Republican presidential nomination, publicly praised the Russian autocrat while denouncing the American president, declaring, "I will tell you that, in terms of leadership, [Putin's] getting an 'A' and our president is not doing so well."October 15, 2015: After an international consensus emerged that pro-Russian forces in Ukraine shot down Malaysian Airlines Flight 17, killing nearly 300 people, Trump stressed Russia's denial, adding, "No one really knows who did it."December 17, 2015: At an annual press conference, Putin sang Trump's praises. Though precise translations vary, by one account, the Russian president said of the Republican, "He's a really brilliant and talented person, without any doubt. It's not our job to judge his qualities, that's a job for American voters, but he's the absolute leader in the presidential race."December 18, 2015: Trump appeared on MSNBC and was asked about Putin's habit of invading countries and killing critics. "He's running his country, and at least he's a leader," Trump replied, "unlike what we have in this country." Reminded that Putin has been accused of ordering the murder of journalists, Trump replied, "Well, I think our country does plenty of killing also."April 20, 2016: Trump elevated Paul Manafort, a Republican lobbyist with longstanding ties to Putin's government in Russia, to serve as his campaign chairman.April 27, 2016: Trump delivered a speech outlining his foreign-policy vision and vowed to ease "tensions" between Russia and the United States, and end "this horrible cycle of hostility." While the GOP candidate talked about all of the things he expects countries like China and Mexico to do to make a Trump administration happy, he made no comparable demands of Russia or its leaders.May 5, 2016: Trump sat down for an interview with Fox News' Bret Baier, who asked if he'd ever spoken directly to Vladimir Putin. "Yeah, I have no comment on that," Trump replied. "No comment." Reminded that he rarely shies away from questions, the presidential candidate added, "Yeah, but I don't want to comment."July 13, 2016: Delegates to the Republican National Convention reported that Trump campaign officials quietly worked behind the scenes to make the party's platform more in line with Russia's preferences. One GOP congressman was quoted saying soon after that the "most under-covered story of convention" was Team Trump's efforts to change the party platform "to be more pro-Putin."July 20, 2016: The New York Times asked Trump if he'd honor the NATO treaty and defend allied nations if attacked. Trump balked -- saying he'd check first to see if he's satisfied with their contributions to the alliance. "We have many NATO members that aren't paying their bills," he said. (Putin, of course, is a fierce NATO critic.)July 24, 2016: Hillary Clinton's campaign manager, Robby Mook, told ABC News, "Experts are telling us that Russian state actors broke into the DNC.... It's troubling that some experts are now telling us that this was done by the Russians for the purpose of helping Donald Trump." The same day, a Washington Post report added, "In the past 24 hours, cybersecurity experts have said that the email cache released by WikiLeaks on Friday appears to have been given to the anti-secrecy group by Russian intelligence."July 27, 2016: In a move without precedent in American history, Trump held a press conference in which he publicly urged Putin's espionage services to help sabotage the Clinton campaign and help put Trump in the White House.July 31, 2016: Following a series of contradictory statements about the nature of his connections with Putin -- at different times, Trump said he "got to know him very well," followed by, "I don't know who Putin is" -- the Republican candidate was asked to clarify. Trump responded, "I had -- no, I -- look. What do you call a relationship?"July 31, 2016: In the same interview, Trump conceded that people on his team may have weakened the Republican platform to be more in line with Putin's wishes.September 23, 2016: Yahoo News reported that Carter Page, a Trump foreign policy adviser, was suspected by U.S. intelligence officials of having "opened up private communications with senior Russian officials -- including talks about the possible lifting of economic sanctions if the Republican nominee becomes president."September 26, 2016: Despite having been briefed by intelligence officials on Russia's role in the DNC hack, Trump declares at a debate, "I don't think anybody knows it was Russia that broke into the DNC. [Clinton's] saying, 'Russia, Russia, Russia,' but I don't -- maybe it was. I mean, it could be Russia, but it could also be China. It could also be lots of other people. It also could be somebody sitting on their bed that weighs 400 pounds, OK?"October 9, 2016: During the second presidential debate, Trump announced that he disagreed with his own running mate about "provocations by Russia" needing to be met "with American strength." Trump specifically said, "[Mike Pence] and I haven't spoken, and I disagree."October 9, 2016: At the same event, despite having already speculated about the source of the DNC hack, Trump declared, "Maybe there is no hacking."October 17, 2016: Trump complained that Clinton's rhetoric towards Putin was too "tough," and she shouldn't be so quick to "insult" the Russian leader. Trump added, "If I win on Nov. 8, I could see myself meeting with Putin and meeting with Russia prior to the start of the administration."October 19, 2016: In the final presidential debate, Clinton explained that Putin would "rather have a puppet as president of the United States." Trump responded, "No puppet. No puppet. You're the puppet. No, you're the puppet."October 19, 2016: In the same debate, the moderator asked Trump if he rejects the assessments from U.S. intelligence officials about Russia's U.S. cyber-attack. The Republican replied, "Yeah, I doubt it. I doubt it."October 27, 2016: The same day Trump complained it's not "smart" for Clinton to speak "badly" about Putin, the Russian president publicly praised the Republican candidate. "He represents the interests of the part of the society tired of the elites that have held power for decades," Putin said.November 10, 2016: Despite denials from Trump campaign officials, Russian Deputy Foreign Minister Sergei Ryabkov said "there were contacts" between the Russian government and Trump's team before the U.S. presidential election. Further contradicting the Republican campaign's claims, Ryabkov added that "quite a few" members of Trump's team "have been staying in touch with Russian representatives" ahead of the American election.November 23, 2016: McClatchy reported that Trump had spoken directly with Putin after the U.S. election more than he'd talked to any other foreign leader.December 3, 2016: Viktor Nazarov, the governor of Omsk, Russia, declared in a radio interview, "It turns out that United Russia won the elections in America."December 4, 2016: Putin again publicly praised Trump, telling a Russian television station, "Because he achieved success in business, it suggests that he is a clever man."December 9, 2016: Confronted with reports that the CIA believes Russia tried to help elect Trump, Trump's transition team issued a statement -- which didn't include a denial -- criticizing U.S. intelligence agencies.December 11, 2016: Trump said he's considering ExxonMobil CEO Rex Tillerson, Putin's closest American ally, to be his Secretary of State nominee, in part because Tillerson "does massive deals in Russia."Expect this timeline to grow as Trump's presidency gets underway next month.