Vice President Mike Pence put the blame for 2016 election interference squarely on Russia and pledged that the Trump administration would step up efforts to deter cyberattacks against U.S. democracy.

“While other nations possessed the capability, Russia meddled in our 2016 election,” Mr. Pence said Tuesday in his first significant speech about cybersecurity. “That is the unambiguous judgment of our intelligence community, and as the president said, we ‘accept the intelligence community’s conclusion.’ ”

Mr....