The Department of Homeland Security mounted an “inadequate” response to counter a Russian government-affiliated campaign preparing to undermine confidence in the American voting process, the Senate Intelligence Committee determined in an interim report released Tuesday detailing recommendations for how to improve election security across states and systems.

The interim report, which identified at least 18, and potentially as many as 21, states whose election systems were targeted, is the first of four installments the committee is planning to release as part of its ongoing investigation into Russian interference during the 2016 elections, before concluding a final report in the fall that will address the greater themes of the investigation, including allegations of collusion between affiliates of President Trump and Russian officials. The other three, according to panel chairman Sen. Richard Burr (R-N.C.), will address the intelligence committee’s assessment of Russia’s actions and intentions, the conduct of the Obama administration, and the exploitation of social media, in that order. The first of the three, an interim report on the intelligence community’s assessment of Russian interference, will be released next week, Burr said.

Late last month, the Republican majority of the House Intelligence Committee released its final Russia report, finding that the intelligence community did not adhere to its best practices when it determined that Russia had interfered in the U.S. election with the aim of aiding Trump. When asked whether the Senate Intelligence Committee’s interim report might make the same determination, Burr said: “I’m not sure that the House was required to substantiate every conclusion with facts.”

“We may have different opinions but whatever we propose, whatever we assess, we’re going to have the facts to show for that,” Burr added.

Tuesday’s report follows the panel’s publication of recommendations to improve election infrastructure, which include a plea for DHS to “expedite security clearances for appropriate state and local officials” to better improve coordination with the federal government. The panel held a hearing with federal officials to review those recommendations in March.

While the report chastises the DHS of both the Trump administration and the Obama administration for a slow response — pointing out it took committee pressure and until September 2017 for the department to reach out to chief elections officials in each state that had been targeted — it also congratulates the agency for making “tremendous progress” over the past six months.

The report says that states should remain the primary entities running elections. But it also recommends committing more money to those efforts, urges the establishment of minimum standards that voting machines have a per-vote paper trail and no WiFi capability, and encourages states to improve the security surrounding their election systems, which Russian actors successfully penetrated, according to the panel’s findings.

In “a smaller number of states,” the report found, cyber infiltrators could have altered or deleted voter registration data — though in no cases, senators wrote, were cyber actors in a position to manipulate individual votes or vote totals.

The committee also warned in the report that while Russia was clearly planning on undermining confidence in voting systems, they could not determine whether cyber actors stopped short of exploiting certain vulnerabilities because they “decided against taking action, or whether they were merely gathering information and testing capabilities for a future attack.”

“Regardless, the Committee believes the activity indicates an intent to go beyond traditional intelligence collection,” the senators wrote.