President Donald Trump spent the first two years of his presidency doing something Russian leaders have attempted since 1949: pushing NATO to the brink of irrelevance.

Now it's come out that the FBI reportedly investigated Trump as a possible Russian asset as he publicly and privately talked about withdrawing from the alliance.

Trump has succeeded where decades of Russian nuclear saber rattling, spying, assassinations, and information warfare have failed to fray the alliance.

According to experts, Russian President Vladimir Putin is loving Trump's attacks on NATO, and a former NATO supreme commander called Trump's talk the "gift of the century" for the Russian leader.

President Donald Trump spent the first two years of his presidency doing something Russian leaders have attempted since 1949: pushing NATO to the brink of irrelevance.

And Trump reportedly did so while under investigation by the FBI as a possible Russian agent all along.

A trio of bombshell reports gave depth to years of reporting and public spectacles that indicate Trump has an openly antagonistic, skeptical view of the military alliance that’s expanded American power and deterred a great war in Europe for 70 years.

First, the New York Times reported that the FBI began investigating the possibility that Trump could be Russian asset after he fired FBI Director James Comey. Trump has twice made it clear that Comey’s dismissal was at least in part owed to his refusal to drop the Russia probe.

It's publicly known that Trump is under an obstruction-of-justice investigation tied to his firing of Comey.

Read more: Meet Marina Gross, the interpreter who was the only other American in the room for Trump and Putin's 1-on-1 meeting in Helsinki

Trump’s presidential campaign maintained a dense web of ties to Russia, and 33 Trump associates have been charged with crimes, while his former lawyer, his campaign chairman, and his national security adviser have all been cooperating with an investigation into whether Trump conspired with Russian President Vladimir Putin to win the election.

Second, the Washington Post reported over the weekend that Trump has gone to "extraordinary lengths" to conceal details of his conversations with Putin from senior officials in his administration.

Third, a report from The Times cited senior administration officials as saying that several times throughout 2018, Trump privately said he wanted out of NATO. On Twitter, Trump has publicly waved that possibility repeatedly.

Read more: Trump torches allies, threatens NATO pullout after tense WWI memorial trip to Paris

Retired Adm. James G. Stavridis, the former supreme allied commander of NATO, told The Times that the US backing out of the alliance would be "a geopolitical mistake of epic proportion."

"Even discussing the idea of leaving NATO — let alone actually doing so — would be the gift of the century for Putin," he continued.

But Trump has, ad nauseam, discussed backing out of NATO and attacked the alliance's core principals, and experts say Putin is loving it.

Disappearing Article 5

Trump speaks in Warsaw, Poland. Evan Vucci/AP

The main point of NATO is Article 5, which says that if one member nation gets attacked, that nation can count on the collective defense of all NATO members.

Only one nation has ever called for the full force of a mutual NATO response: The US in the aftermath of the September 11, 2001, terror attacks. To this day, troops from NATO countries across Europe fight and die alongside US forces in Afghanistan as a result.

Read more: Here's how Donald Trump took shots at NATO in 2018 — and it spurred Jim Mattis to quit in protest

But standing in front of twisted steel left over from the wreckage of ground zero at an event honoring Article 5, Trump reportedly refused to speak a line in a written speech honoring that clause.

Trump campaigned on calling NATO "obsolete" and demanding the alliance’s 29 members meet a defense-spending goal set for 2024 immediately. He then tried to double that spending goal.

Trump brought a NATO meeting in Brussels into an emergency session after reportedly becoming undiplomatic with German Chancellor Angela Merkel.

Trump suggested that Montenegro — NATO’s newest and smallest member that has accused Russia of trying to assassinate its president — might cross over four countries to attack Russia because of the “aggressive” nature of its 622,000 inhabitants.

Trump then questioned why US soldiers should fight to defend Montenegro, a fledgling democracy struggling to fend off Russian influence.

Read more: Trump fundamentally undermines NATO, says 'aggressive' Montenegro could attack Russia to start World War III

In short, Trump has succeeded where decades of Russian nuclear saber rattling, spying, assassinations, and information warfare have failed: to fray the world's foremost alliance, whose mission is to counter Russia.

"Trump’s criticisms of the alliance and the divisive steps he’s taken have made Europeans trust the US less, question the US alliance, and really helped Putin’s efforts to weaken NATO," Jorge Benitez, the director of the Atlantic Council’s NATOSource, told Business Insider.

But Trump has a point

Merkel has since said that Europe can no longer rely on the US. Along with French President Emmanuel Macron, she has endorsed the plan for a European army, though experts agree that the idea is dubious to the point of being incredible and that such an army would likely not be strong enough to stand up to Russia.

US presidents for decades have urged NATO members to spend more on defense and contribute more to the alliance. NATO members that border Russia typically spend more on defense, while countries like Germany don't spend anywhere near the 2% they committed to hit by 2024 and have shown almost no willingness to spend more.

Read more: Macron's 'real European army' sounds like a 'nonsense' force that would never deploy

But Trump's approach to NATO looks more like a shakedown than a call to arms. Trump has insisted that NATO owes back pay for not meeting spending commitments during years that weren't included in the agreement.

"Other presidents have talked about making the alliance fairer, but Trump is talking about ending the alliance," Benitez said.