President Barack Obama’s administration Thursday imposed sanctions against Russian officials and state institutions in retaliation for hacking Democratic Party e-mails, the first public retaliation for what U.S. officials have said was an unprecedented attempt to interfere with the 2016 presidential election. Among those targeted were officials of GRU, Russia’s military intelligence agency, which cybersecurity experts in the U.S. have linked to the hacking of the Democratic National Committee and party officials through a group they have nicknamed APT 28 or Fancy Bear. The U.S. also is sanctioning some Russian state institutions and cyber companies associated with them. To impose the penalties U.S. will expand a 2015 executive order issued by the President Barack Obama, widening his ability to impose economic penalties due to a cyberattack. The hackers leaked the pilfered e-mails in a bid to damage the campaign of Democratic presidential candidate Hillary Clinton, according U.S. intelligence agencies. She lost to Republican Donald Trump who has repeatedly scoffed at the finding that Russia was behind the cyberattacks. The moves will ratchet up tensions with Russia less than a month before Trump’s inauguration. The president-elect, who has said the hacking could have been the work of “somebody sitting in a bed someplace,” told reporters Wednesday that “we ought to get on with our lives.” They also raise the possibility of an escalating cycle of finger-pointing and retaliation between Washington and Moscow despite Trump’s pledge to seek better relations with Putin. The Russian government, which has denied responsibility for the hacking, has vowed to respond to any new sanctions with unspecified counter-measures. The actions announced Thursday may be matched by covert countermeasures intended to warn Russia that the U.S. is able to breach its most sensitive computer systems, while preserving public deniability. “If I want to just quietly take out their capability and send a very sneaky message and not an overt message, I would probably do a covert action,” Bob Stasio, a fellow at the Truman National Security Project and former chief of operations at the National Security Agency’s cyber operations center, said in advance of Thursday’s announcement. U.S. relations with Putin’s government have deteriorated over Russia’s military intervention in Ukraine on behalf of separatist rebels and in Syria to bolster the regime of President Bashar al-Assad. The U.S. and European allies imposed sanctions over Russia’s moves in Ukraine and its annexation of Crimea, targeting Russia’s financial services, energy, metals and mining, defense, and engineering sectors. The Justice Department has used indictments in the past to target foreign officials it believes participated in cyberattacks. In 2014, a grand jury indicted five Chinese military hackers the Obama administration alleges stole trade secrets and internal communications from an American business. Seven Iranians were indicted earlier this year for a series of cyberattacks against the U.S. financial system and a U.S. dam in New York state three years ago. Commenting before the Obama administration’s announcement, Trump transition spokesman Sean Spicer said Thursday if the government has any proof of foreign interference in the election, it should make that evidence known. “Right now we need to see further facts based on what we do know and what’s in the public domain,” Spicer told reporters on a conference call. The Trump transition team released a letter this month to Trump from Putin in which the Russian leader offered holiday greetings and said he hoped to work more cooperatively with the incoming administration. “A very nice letter from Vladimir Putin; his thoughts are so correct,” Trump said in a statement released alongside the Dec. 15 letter. “I hope both sides are able to live up to these thoughts, and we do not have to travel an alternate path.” Despite Trump’s admiration for the Russian leader, members of both parties in Congress have expressed alarm about the campaign hacking and vowed to conduct hearings into Russia’s role. “I’m going after Russia in every way we can go after Russia,” Republican Senator Lindsey Graham of South Carolina, a member of the Senate Armed Services Committee, said on CNN this month. “I think they did interfere with our elections, and I want Putin personally to pay a price.”