U.S. Targets North Korea in Retaliation for Sony Hack

New Sanctions Target Individuals Working for Arms Industry.

The Obama administration renewed a U.S. campaign of financial pressure against North Korea, imposing sanctions against the country’s lucrative arms industry in what American officials said was a first step in retaliation for Pyongyang’s alleged cyberattack on Sony Pictures Entertainment.

President Barack Obama signed an executive order on Friday widening his authority to further punish a country that is already the world’s most isolated. The move returns the U.S. to a posture of open hostility with its oldest remaining Cold War adversary after the American leader last month initiated a détente with Cuba.

Treasury Secretary Jacob Lew said the moves were designed to “further isolate key North Korean entities and disrupt the activities of close to a dozen critical North Korean operatives.” He said the U.S. would defend its businesses and citizens from “attempts to undermine our values or threaten the national security of the United States.”

The new moves come despite lingering questions over whether North Korea was behind the November attack by hackers who released thousands of embarrassing internal emails and threatened Sept. 11-like attacks on movie theaters if the studio released “The Interview,” a comedy about the assassination of North Korea’s leader Kim Jong Un. The Obama administration has discounted those attacks.

Some nongovernmental cybersecurity experts have challenged the U.S. conclusion that North Korea was behind the hacking, arguing the attack would make more sense as the work of an aggrieved former Sony employee. Some security researchers not involved in the Sony probe argue the government didn’t prove its case.

However, the White House has stood by the Federal Bureau of Investigation’s assessment. “We remain very confident in the attribution,” an administration official said Friday during a conference call with reporters.

More From The Wall Street Journal (subscription required):