One of these steps was the approval for Ukrainian forces to use Western missiles on Russian territory, specifically ATACMS and British-French Storm Shadow/Scalp.
As noted by Dov Zakheim, a senior advisor at the Center for Strategic and International Studies, for The Hill, this move is a direct response to the activation of Russian troops in the Kursk region, where experts estimate around 10,000 North Korean soldiers are stationed. More importantly, it seems that Biden has decided no longer to heed Putin's nuclear threats. Perhaps throughout his presidency, he has come to realize that nuclear escalation from the Kremlin has not materialized.
In light of Ukraine's initial strikes on Russian territory using ATACMS, Putin officially signed changes to Russia's nuclear doctrine, stating that attacks on Russian territory are now considered a direct threat to NATO. However, as Zakheim points out, the decision to use nuclear weapons has always rested with Putin himself, and he has not dared to escalate the situation despite all warnings.
"In reality, the Kremlin has merely engaged in bluster," the expert notes.
Dov Zakheim emphasizes that had the U.S. made such decisions regarding Ukraine a few years earlier, the war could have ended much sooner.
Source: thehill .
Politeka also reported on this matter.