Opinion | Mueller Hints at a National-Security Nightmare

An intelligence assessment makes two determinations: a conclusion about the type of influence a foreign power may have over an individual and the degree of confidence in that conclusion. For example, when Mr. Trump boasted to the Russian foreign minister and ambassador in the Oval Office that he had fired the F.B.I. director, it raised only the possibility — a “circumstantial inference,” as it’s called in counterintelligence — that the president was wittingly working on behalf of the Russians.

This apparent desire to please these officials indicates a high level of Russian influence and, in the context of other actions that pleased Mr. Putin, like his sudden decision to withdraw American troops from Syria — could support a modest to high level of confidence in that conclusion.

But reaching very high confidence that Mr. Trump is wittingly doing Moscow’s bidding would require something we don't have and would not expect to have, like an email from Vladimir Putin ordering Mr. Trump to fire the F.B.I. director James Comey.

Similarly, there is no "smoking gun" order in the incidents below. They indicate a strong influence by the Russians, but only low to moderate confidence that he acted at Russia’s behest. There’s simply no clear sign that Mr. Trump was following directions of acting under pressure from the Kremlin.

The former Trump adviser Roger Stone directly communicates with the Russia-linked actor Guccifer 2.0 and coordinates with WikiLeaks to get Mr. Trump elected — and he is likely aware that one is a Russian front organization and the other is working with the Russians.

A Trump campaign national security adviser is informed by a Russian intelligence operative that the Kremlin has stolen Hillary Clinton-related emails and could assist the Trump campaign through “anonymous release” of derogatory information; the campaign then works on setting up backdoor meetings with senior Russian government officials (though the meetings do not materialize).

Members of the Trump transition team conduct secretive, back channel meetings with Putin operatives.

Mr. Trump and Mr. Putin speak alone in Helsinki, then Mr. Trump accepts Mr. Putin’s claim that he didn’t meddle in the 2016 election and repudiates the intelligence community’s assessments to the contrary.

Those incidents raise the possibility that Mr. Trump has wittingly sought to advance Russian interests, but the evidence is merely circumstantial and consequently suggests low to moderate confidence in that assessment. In many but not all respects, witting assets can be more dangerous because they have deliberately entered into some sort of understanding or agreement to work on behalf of the foreign power’s interests.

But unwitting assets pose their own dangers. They have significant vulnerabilities that can be exploited with minimal actual coordination. In other words, they look and act more like puppets.