WASHINGTON (AP) — The White House says it is preparing additional “major sanctions” on Russia in response to opposition leader Alexei Navalny's death in an Arctic penal colony.

National Security Council spokesman John Kirby said Tuesday that the new package would be unveiled this Friday. He declined to detail the new actions, citing U.S. government policy, or share how they would expand on the already stiff sanctions the U.S. and its allies have put on Russia in retaliation for its invasion of Ukraine.

Kirby said only that the sanctions, which will coincide with the two year anniversary of Russia's invasion, will be "specifically supplemented with additional sanctions regarding Mr. Navalny's death.”

Kirby said the U.S. had not determined how Navalny had died, but insisted that the ultimate responsibility lies with Russian President Vladimir Putin.

“Regardless of the scientific answer, Putin’s responsible for it," he told reporters.