Some Obama White House officials had little faith that a Trump administration would make good on such pledges, and the efforts to preserve the intelligence continued until the administration's final hours. This was partly because intelligence was still being collected and analyzed, but it also reflected the sentiment among many administration officials that they had not recognized the scale of the Russian campaign until it was too late.
The warning signs had been building throughout the summer, but were far from clear. As WikiLeaks was pushing out emails stolen from the Democratic National Committee through online publication, American intelligence began picking up conversations in which Russian officials were discussing contacts with Trump associates, and European allies were starting to pass along information about people close to Mr. Trump meeting with Russians in the Netherlands, Britain and other countries.
But what was going on in the meetings was unclear to the officials, and the intercepted communications did little to clarify matters — the Russians, it appeared, were arguing about how far to go in interfering in the presidential election. What intensified the alarm at the Obama White House was a campaign of cyberattacks on state electoral systems in September, which led the administration to deliver a public accusation against the Russians in October.
But it wasn't until after the election, and after more intelligence had come in, that the administration began to grasp the scope of the suspected tampering and concluded that one goal of the campaign was to help tip the election in Mr. Trump's favor. In early December, Mr. Obama ordered the intelligence community to conduct a full assessment of the Russian campaign.
