The most unforgettable image of the week was the look on the face of Dan Coats, U.S. director of national intelligence, when NBC correspondent Andrea Mitchell read him a breaking news bulletin that Vladimir Putin had been invited to the White House.

"Say that again!" Coats exclaimed, shaking his head.

The nation's top intelligence official had been blindsided by President Trump, never consulted or informed of this invitation, no doubt because he would have warned against it. And Trump still hasn't told Coats what he promised Putin in their one-one-one meeting with only interpreters present.

Why should we be surprised?  The president's bizarre behavior at Helsinki and since has made moot the question of whether he colluded with Putin's election meddling in 2016.

>> READ MORE: Trump surrenders to Putin at Helsinki summit | Trudy Rubin

Trump is colluding with Putin now.

Whether from blackmail or ego, the U.S. president is actively aiding Kremlin efforts to undermine U.S. institutions. His war on his own intelligence and law enforcement agencies is a perfect example of how he is advancing Russia's goals.

Trump went to Helsinki unprepared and ignored his briefers, leaving himself open to manipulation by a shrewd ex-KGB colonel who masters details.  "I guarantee that Vladimir Putin was prepared for that meeting and knew what buttons he was going to push [with Trump]," said Mike Rogers, the former GOP chair of the House Intelligence Committee.  "You must have an agenda.  To go just to make friends or have a selfie is dangerous policy."

Putin's public remarks contained many digs at U.S. intelligence agents and the Mueller investigation, insinuating they were plotting against Trump.  He was clearly playing to Trump's conspiratorial suspicions about the "deep state."

Trump's humiliation of Coats (a popular former GOP senator whom the president says he admires) is another win for Putin. Last week the president also insulted three former intelligence chiefs — John Brennan, Michael Hayden, and James Clapper — for criticizing his refusal to confront Putin over Russian election meddling.  Clapper confirmed that Trump was shown detailed evidence in January 2017 that Putin personally directed this cyber-espionage.

What better gift could Trump give Putin than to undermine the agencies that have detailed Russian spying? "This was the summit Putin waited for his entire life," says Russia expert Alina Polyakova of the Brookings Institution. "He entirely set the agenda."

>> READ MORE: Trump's homage to Putin at Helsinki proves him unfit to make foreign policy | Trudy Rubin

Putin was probably astonished at how easily he could roll Trump: The president repeatedly praised Putin's outrageous suggestion that Russian security agents be allowed to interrogate U.S. officials whom Putin dislikes, including a former U.S. ambassador to Moscow, Mike McFaul.

The White House only reluctantly retracted this infamous idea after the Senate passed a 98-0 resolution denouncing it.  But White House spokeswoman Sarah Sanders said it had been a "sincere offer." This illustrates how neatly Putin has penetrated Trump's mind.

The danger is multiplied by the president's determination to act without advice from advisers. The Kremlin (which no doubt taped the meeting) has been able to control the global narrative by leaking what supposedly happened in the private meeting in Helsinki, claiming Trump adopted Putin's positions on western Ukraine and Syria.  This stirs further fears amongst America's allies who also don't know what really happened.

What we do know is what Putin hopes to achieve.

In January 2017, the joint intelligence report on election meddling that Trump received warned: "The Kremlin sought to advance its longstanding desire to undermine the US-led liberal democratic order."  Putin is manipulating Trump to help him accelerate that order's demise.

In conversations with Russian foreign-policy experts in Moscow, I've been told that Putin believes the "collective West" that emerged after World War II is collapsing, including the NATO alliance and the European Union. If he can get Trump's help in weakening the EU — which still resists Putin's expansionist goals — all to the good.

Looking ahead, the Kremlin chief sees a future world run by a configuration of big world powers with the United States presenting the main challenge to Russia.  But Putin also sees U.S. democracy as troubled, while (illiberal) Russia is more stable.

The Russian leader hopes to exploit divisions within America, and undermine its institutions, with help from Trump. If he can prevent a strong U.S. pushback against cyber-espionage (which Trump refuses to direct), that's the frosting on the cake.

Thus, at Helsinki, Putin's agenda was clear:  further undermine Mueller and accelerate Trump's break with the U.S. intelligence community.  Most clever, play on Trump's illusion that the ex-KGB agent can be a good partner. "Hopefully someday he'll be a friend," Trump foolishly said of Putin.

Putin didn't have to try hard.  Trump pandered.  Despite indictments that track right back to Putin, Trump invited the Russian leader to the White House in the fall, to coincide with elections in which the Kremlin is still meddling.

"Useful Idiot" is a political term for a person who is manipulated into serving a political cause that is not their own. It used to be applied to naifs who mouthed Soviet propaganda.  Now it fits Trump.