The US has imposed sanctions against Russian President Vladimir Putin's inner circle, including his daughters.
The list also includes the family of Foreign Minister Sergei Lavrov and major banks.
The measures follow new revelations of atrocities by Russian troops in Ukraine, including images of bodies of civilians scattered on the streets of Bucha, near the capital Kyiv.
Russia says, without evidence, the images are staged by Kyiv officials.
Even though satellite images have shown the civilians were killed when Russians were in control of Bucha, Mr Putin on Wednesday described the event as a "crude and cynical provocation by the Kyiv regime".
Referring to the Bucha murders, US President Joe Biden said on Wednesday: "There's nothing less happening than major war crimes."
"Responsible nations have to come together to hold these perpetrators accountable," Mr Biden added.
The US said that Mr Putin's daughters, Katerina Vladimirovna Tikhonova and Maria Vladimirovna Vorontsova, were being put under sanctions "for being the adult children of Putin, a person whose property and interests in property are blocked".
Who are Putin's daughters?
The announcement described Ms. Tikhonova as "a tech executive whose work supports the GoR [Russian government] and defense industry".
Her sister, Ms. Vorontsova, it went on, "leads state-funded programs that have received billions of dollars from the Kremlin toward genetics research and are personally overseen by Putin".
Asked why the US was targeting Mr Putin's daughters, a senior Biden administration official said the US thought they could be in control of some of their father's assets.
"We have reason to believe that Putin, and many of his cronies, and the oligarchs, hide their wealth, hide their assets, with family members that place their assets and their wealth in the US financial system, and also many other parts of the world," the official said.
"We believe that many of Putin's assets are hidden with family members, and that's why we're targeting them."
The US sanctions announced by the White House include:
- economic measures to ban new investment in Russia
- severe financial sanctions on Russia's largest private bank, Alfa Bank, and its largest financial institution, Sberbank
- sanctions on critical major state-owned enterprises
- sanctions on Russian government officials and their family members
Meanwhile the UK has announced further sanctions against eight oligarchs and Russian banks, including the country's largest, Sberbank, and Credit Bank of Moscow.
The European Union is also debating cutting off Russian coal imports as concern over alleged war crimes increases.
Before the new raft of sanctions was announced in Washington, Ukrainian President Volodymyr Zelensky said he could not "tolerate any indecisiveness".
Speaking to the Irish parliament on Wednesday, he said there was still a need to convince some in Europe who believe "war and war crimes are not as horrific as financial losses" to back tougher sanctions.
He added that "Russian oil cannot feed the Russian military machine", with Ukraine's foreign minister arguing on Twitter that an embargo on gas and oil was needed to truly impact Russia's ability to finance the war.
Josep Borrell, the EU's chief diplomat, separately acknowledged on Wednesday that the one billion euros ($1.09bn; £833m) Europe spent on Russian energy every day put into sharp perspective the billion euros given to Ukraine in military assistance since the start of the invasion.
Photo file Caption: Putin's daughter Katerina Tikhonova works in academia and business