WASHINGTON—The U.S. on Thursday levied sanctions on nearly three dozen Russian companies and individuals that the Treasury Department said are helping Moscow evade the West’s economic pressure campaign and aiding the country’s defense and intelligence agencies.

Among those blacklisted include Russia’s largest microchip manufacturer, Mikron, a firm named Serniya Engineering that Treasury said oversaw a network of companies that procured technology and dual-use goods from abroad for the military and intelligence services, and supercomputer company T-Platforms.

The companies were previously identified as sanction targets by The Wall Street Journal. The companies didn’t respond to requests for comment.

The Treasury Department said some of the firms named in the Thursday announcement were shell companies set up to evade prior U.S. sanctions.

The U.S. and its European allies say they are entering a new phase of the sanctions campaign against Russia over its invasion of Ukraine, focusing on tightening enforcement and plugging holes.

“We will continue to target Putin’s war machine with sanctions from every angle, until this senseless war of choice is over,” Treasury Secretary Janet Yellen said in a statement.

The Treasury Department said sanctions targeting “harmful foreign activities of the Russian government” would also apply to Russia’s aerospace, marine and electronics sectors, enabling it to blacklist any company or individual operating in those sectors.

Treasury Secretary Janet Yellen said ‘we will continue to target Putin’s war machine with sanctions from every angle.’

Photo: Alex Wong/Getty Images

Together with strict export controls imposed on broad sectors of Russia’s economy, officials say the sanctions are intended to degrade the country’s growth prospects and undermine the Kremlin’s ability to project its power internationally, including waging war to take over Ukraine.

Russia is attempting to use unsanctioned companies to sidestep the sanctions, U.S. officials said. Closing the gaps in the sanctions regime will amplify the economic and financial pressure campaign.

The sanctions freeze any assets the targets hold within U.S. jurisdiction and prohibit U.S. entities—including foreign companies that have U.S. operations—from conducting transactions with the targets. Entities found violating the prohibitions risk sanctions themselves.

The sanctions imposed by a coalition of Western nations representing nearly two-thirds of the global economy are crippling Russia’s economy. U.S. officials say the campaign could cut Russia’s economic growth in half.

Deputy Treasury Secretary Wally Adeyemo, who is meeting with European officials this week, said the allies are “forcing the Kremlin to choose between spending its dwindling resources on propping up its domestic economy or continuing to finance the invasion of Ukraine and other destabilizing activity.”

Write to Ian Talley at ian.talley@wsj.com