A South Korean army soldier walks near a TV screen showing an advertisement of Sony Pictures Entertainment’s “The Interview” at the Seoul Railway Station. (Ahn Young-Joon/AP)

Two weeks after blaming North Korea for hacking into Sony Pictures Entertainment, the Obama administration on Friday imposed new sanctions on the repressive government as part of what it described as a broader attempt to tackle threats to U.S. cybersecurity.

Under a new executive order signed by President Obama, the Treasury Department imposed financial measures on 10 North Korean officials and three government agencies. Although it is unclear how those sanctions might deter future cyberattacks, officials said they expected financial institutions in other countries to take notice and to complicate North Korean business dealings.

“This attack on Sony Pictures Entertainment clearly crossed a threshold for us,” said one administration official who spoke on the condition of anonymity because of the sensitivity of the issue. The official, one of four who spoke to reporters on a conference call, cited concerns about the growing sophistication and danger posed by cybersecurity threats in general.

“You should see this as part of a broader effort to raise the baseline level of cybersecurity across the country and tackle these threats head-on.”

The targets of the new sanctions include the Reconnaissance General Bureau, North Korea’s main intelligence agency, which is believed to have orchestrated major cyber-operations. The other targets are the Korea Mining Development Trading Corp., which is North Korea’s main arms dealer, and the Korean Tangun Trading Corp., which is responsible for North Korea’s defense research and development.

“We cannot have a society in which some dictator someplace can start imposing censorship here in the United States,” President Obama said at his end-of-year news conference. (AP)

None of the individuals sanctioned — operating out of Russia, Iran, Syria, China and Namibia — is believed to have been directly involved in the hack into Sony, officials said. They earned their place on the new list as employees of the Pyongyang government or representatives of the ruling Workers’ Party of Korea.

North Korea is already one of the most heavily sanctioned countries in the world, and the agencies and entities targeted Friday have all been sanctioned previously. Still, analysts said the measures could inflict some new financial pain on North Korea’s already isolated military establishment.

In a statement, Treasury Secretary Jack Lew said the new sanctions aim to hold North Korea responsible for “destructive and destabilizing conduct.”

“Even as the FBI continues its investigation into the cyber- attack against Sony Pictures Entertainment, these steps underscore that we will employ a broad set of tools to defend U.S. businesses and citizens, and to respond to attempts to undermine our values or threaten the national security of the United States,” he said.

Obama had pledged to respond “proportionally” to the intrusion into Sony’s network — an attack that not only exposed embarrassing corporate e-mails but also wiped out computer data. The new measures fall short of the response sought by some lawmakers, including a move to redesignate North Korea as a state sponsor of terrorism.

Regardless of their impact, however, the sanctions serve as a sign of the administration’s confidence that North Korea was behind the attack against Sony.

Since the earliest news reports about possible North Korean responsibility in November, there has been skepticism among independent security researchers who say that it is notoriously difficult to determine the origins of cyberattacks and that sophisticated hackers can hide their footsteps or otherwise fool investigators.

Sony Pictures Entertainment’s “The Interview” is more than a satire on North Korea’s Kim Jong Un. It also parodies journalists and the CIA. Post opinion writer Alyssa Rosenberg provides commentary on the film’s humorous intentions. (Jayne W. Orenstein and Alyssa Rosenberg/The Washington Post)

Those doubts have not receded since the FBI officially laid blame on the reclusive nation on Dec. 19, the same day that Obama threatened to retaliate for the attack and chastised Sony for canceling the planned release of the movie “The Interview.” The comedy’s plot is built around the assassination of North Korean leader Kim Jong Un.

But administration officials insist they remain confident that North Korea, also known as the Democratic People’s Republic of Korea, is behind the hack. They note that they have access to intelligence that skeptics do not, some of it gathered by the nation’s top spy analysts.

“We stand firmly behind our call that the DPRK is behind the attacks on Sony,” a senior administration official said Friday.

Officials said they believed the new measures marked the first time the United States has imposed sanctions related to a cyber­attack, though some sanctions in the past have been connected to the use of the Internet in human rights abuses.

Marcus Noland, an expert on North Korea at the Peterson Institute for International Economics, said that the latest sanctions escalate a broader campaign that has achieved mixed results. Punitive economic measures have not forced fundamental change in Pyongyang, Noland said, but they have “impeded” key activities, including North Korea’s efforts to sell its missile systems through illicit foreign markets.

“There is some evidence that these [sanctions] have worked in disrupting North Korea’s exports of military goods and services,” Noland said. “There is less evidence, at least in the public domain, that they have been successful in disrupting North Korea’s imports of key components to its missile or nuclear programs.”

Despite its isolation, North Korea relies on ties to a network of financial institutions beyond its borders, mostly in China. Mainstream banks wanting access to the United States have largely severed ties to North Korea, but smaller regional institutions have been willing to work with Pyongyang, Noland said.

The new sanctions come just days after Kim delivered a public address with conflicting messages toward the West. He raised the prospect of high-level meetings with senior officials from South Korea — a step that Washington has long encouraged — but also included defiant language aimed at the United States and dismissing Washington’s criticism of North Korea’s human rights record.

Craig Timberg contributed to this report.