A top Democratic senator briefed by Twitter on Russia and the 2016 election called the company’s explanation ‘frankly inadequate’

Sen. Mark Warner delivered a full verbal lashing of Twitter on Thursday for providing “inadequate” details to Congress about the misinformation spread on its platform by Russian sources during the 2016 presidential election.

Hours after Twitter briefed Warner’s aides and others on the Senate Intelligence Committee — a panel that is investigating the Kremlin’s potential meddling in U.S. politics — Warner said he felt that Twitter did not grasp the seriousness of the panel’s probe.

At issue for Warner is the fact Twitter searched its records based only on information already unearthed by Facebook.

Earlier this month, Facebook found about 470 accounts with Russian ties had purchased 3,000 ads designed to stoke religious, racial and social unrest in the U.S. before Election Day. Twitter used those conclusions as a basis for its own probe, revealing today that it found about 200 related accounts with dubious Russian links.

“I understand Facebook and Twitter have very different business models and very different approaches to how they utilize the internet,” began Warner, the intelligence committee’s top Democratic lawmaker. “But the presentation that the Twitter team made to the Senate Intel staff today was deeply disappointing.”

“The notion that their work was basically derivative, based upon accounts that Facebook had identified, showed an enormous lack of understanding from the Twitter team of how serious this issue is, the threat it poses to democratic institutions, and again, begs many more questions than they [answer],” Warner continued at a press conference held on Capitol Hill.

For that reason, Warner said, it is all the more important for Twitter to “come forward in a public presentation and explain to the Senate and the American public.”That’s a reference to his committee’s scheduled Nov. 1 hearing with the tech giant and its peers, Facebook and Google — a session that could subject Twitter to another thrashing.

The House Intelligence Committee, meanwhile, is aiming to hold its own hearing this October. And that panel’s top Democratic lawmaker, Rep. Adam Schiff, similarly urged Twitter to do a deeper dive — and figure out to what extent Russian forces tapped its platform.

“At this early stage in their internal review, Twitter has identified and taken remedial steps against accounts linked to Russian government actors,” Schiff said. “Much of the information that Twitter used to identify Russian-linked accounts, however, was derived from Facebook’s own analysis, and it is clear that Twitter has significant forensic work to do to understand the depth and breadth of Russian activity during the campaign.”

Schiff also offered one specific area where Twitter should start. “This additional analysis,” he said, “will require a far more robust investigation into how Russian actors used their platform as a part of their active measures campaign and whether any of the targeting on Twitter suggests the possibility of assistance or collusion with any U.S. persons.”

This article originally appeared on Recode.net.