HONOLULU -- The United States struck back Thursday at Russia for hacking the U.S. presidential campaign with a sweeping set of punishments targeting Russia's spy agencies and diplomats. The U.S. said Russia must bear costs for its actions, but Moscow called the Obama administration "losers" and threatened retaliation.

A month after an election the U.S. says Russia tried to sway for Donald Trump, President Barack Obama sanctioned the GRU and FSB, leading Russian intelligence agencies the U.S. said were involved. Those sanctions easily could be pulled back by Trump, who has insisted Obama and Democrats merely are attempting to delegitimize his election.

In an elaborately coordinated response by at least five federal agencies, the Obama administration also sought to expose Russia's cyber tactics with a detailed technical report and hinted it still might launch a covert counterattack.

"All Americans should be alarmed by Russia's actions," Obama said, adding, "Such activities have consequences."

Trump issued a statement saying it was "time for our country to move on to bigger and better things."

Yet in the face of newly public evidence, he suggested he was keeping an open mind.

"In the interest of our country and its great people, I will meet with leaders of the intelligence community next week in order to be updated on the facts of this situation," Trump said.

As part of the punishment, the U.S. also kicked out 35 Russian diplomats the U.S. said were actually intelligence operatives and shut down a pair of Russian compounds in New York and Maryland.

The U.S. said those actions were in response to Russia's harassment of U.S. diplomats, calling it part of a pattern of aggression that included the cyberattacks on the Democratic National Committee and Hillary Clinton's campaign chairman.

It was the strongest action the Obama administration has taken to date to retaliate for a cyberattack and more comprehensive than last year's sanctions on North Korea after it hacked Sony Pictures Entertainment.

The new penalties add to existing U.S. sanctions over Russia's actions in Ukraine, which have impaired Russia's economy but had limited impact on President Vladimir Putin's behavior.

Russia, which denied the hacking allegations, called the penalties a clumsy yet aggressive attempt to "harm Russian-American ties."

Putin spokesman Dmitry Peskov said Russia would take into account the fact Trump soon will replace Obama as it drafts retaliatory measures.

The day marked a low point for U.S. relations with Russia, which have suffered during Obama's years as he and Putin tussled over Ukraine, Edward Snowden and Russia's support for Syrian President Bashar Assad.

Maria Zakharova, a Russian foreign ministry spokeswoman, took to Facebook to call the Obama administration "a group of foreign policy losers, angry and ignorant."

It was unlikely the new sanctions, while symbolically significant, would have a major impact on Russian spy operations.

The sanctions freeze any U.S. assets and block Americans from doing business with them.

But Russian law bars the spy agencies from having assets in the U.S., and any activities they undertake likely would be covert and hard to identify.

"On its face, this is more than a slap on the wrists, but hardly an appropriate response to an unprecedented attack on our electoral system," said Stewart Baker, a cybersecurity lawyer and former National Security Agency and Homeland Security Agency official.

Senior Obama administration officials said even with the penalties, the U.S. had reason to believe Russia would keep hacking other nations' elections and might try to hack American elections again in 2018 or 2020.