Russian President Vladimir Putin won’t rule out using nuclear weapons if Russia faces an “existential threat,” Kremlin spokesperson Dmitry Peskov said Tuesday in an interview with CNN’s Christiane Amanpour.

Putin previously hinted that the nuclear option was on the table when he said in his televised address announcing the invasion on Feb. 24 that the “consequences” for any nation attempting to interfere “will be such as you have never seen in your entire history.”

Three days after the invasion began, Putin ordered Russia’s nuclear forces to high alert status. Russia has an arsenal of over 6,000 nuclear warheads.

Amanpour also asked Peskov what Putin has achieved in Ukraine so far, to which Peskov replied that Putin “hasn’t achieved yet.” Peskov did, however, claim that Russia’s invasion was “going on strictly in accordance with the plans and the purposes that were established beforehand.”

According to a Russian Defense Ministry report that was released Sunday and almost immediately scrubbed from the country’s media, over 9,800 Russian troops have been killed since the invasion began on Feb. 24. In the past week, some Biden administration officials have concluded Russia has abandoned its original goal of implementing regime change in Ukraine, The Wall Street Journal reported Monday.