Of course, to determine whether collusion occurred, we would have to know whether the Trump campaign continued to meet with Russian representatives subsequent to the June meeting. The early “courting” stage is almost always somewhat open and discoverable. Only after the Russian intelligence officer develops a level of control can the relationship be moved out of the public eye. John Brennan, the former director of the C.I.A., recently testified, “Frequently, people who go along a treasonous path do not know they are on a treasonous path until it is too late.”

Even intelligence professionals who respect one another and who understand the Russians can and often do disagree. On the Trump collusion question, the difference of opinion comes down to this: Would the Russians use someone like Mr. Goldstone to approach the Trump campaign? Our friend and former colleague Daniel Hoffman argued in this paper that this is unlikely — that the Russians would have relied on trained agents. We respectfully disagree. We believe that the Russians might well have used Mr. Goldstone. We also believe the Russians would have seen very little downside to trying to recruit someone on the Trump team — a big fish. If the fish bit and they were able to reel it in, the email from Mr. Goldstone could remain hidden and, since it was from an acquaintance, would be deniable if found. (Exactly what the Trump team is doing now.)

If the fish didn’t take the bait, the Russians would always have had the option to weaponize the information later to embarrass the Trump team. In addition, if the Russians’ first objective was chaos and disruption, the best way to accomplish that would have been to have someone on the inside helping. It is unlikely that the Russians would not use all the traditional espionage tools available to them.

However, perhaps the most telling piece of information may be the most obvious. Donald Trump himself made numerous statements in support of Russia, Russian intelligence and WikiLeaks during the campaign. At the same time, Mr. Trump and his team have gone out of their way to hide contacts with Russians and lied to the public about it. Likewise, Mr. Trump has attacked those people and institutions that could get to the bottom of the affair. He fired his F.B.I. director James Comey, criticized and bullied his attorney general and deputy attorney general, denigrated the F.B.I. and the C.I.A., and assails the news media, labeling anything he dislikes “fake news.” Innocent people don’t tend to behave this way.

The overall Russian intent is clear: disruption of the United States political system and society, a goal that in the Russian view was best served by a Trump presidency. What remains to be determined is whether the Russians also attempted to suborn members of the Trump team in an effort to gain their cooperation. This is why the investigation by the special counsel, Robert Mueller, is so important. It is why the F.B.I. counterintelligence investigation, also quietly progressing in the background, is critical. Because while a Russian disruption operation is certainly plausible, it is not inconsistent with a much darker Russian goal: gaining an insider ally at the highest levels of the United States government.

In short, and regrettably, collusion is not off the table.