That note of alarm sounded by Dan Coats, the director of national intelligence, came on the same day that 12 Russian agents were indicted on charges of hacking the Democratic National Committee and Hillary Clinton’s presidential campaign. Mr. Coats said those indictments illustrated Moscow’s continuing strategy to undermine the United States’ democracy and erode its institutions.

“The warning lights are blinking red again,” Mr. Coats said as he cautioned of cyberthreats. “Today, the digital infrastructure that serves this country is literally under attack.”

Coming just days ahead of President Trump’s meeting with President Vladimir V. Putin of Russia, Mr. Coats’s comments demonstrate the persistent divisions within the administration on Russia — and on how hard a line senior administration officials should take with Moscow on its cyberspace activities.