President Joe Biden’s top intelligence official said Tuesday the U.S. believes Russia underestimated the strength of Ukraine’s resistance before launching an invasion that has likely caused thousands of Russian casualties.

       Director of National Intelligence Avril Haines told a congressional panel that U.S. officials believe Russian President Vladimir Putin feels “aggrieved” by Russia’s failure to subdue Ukraine and that he perceives that he cannot afford to lose the war. But what Putin might consider a victory could change given the escalating costs of the conflict to Russia, Haines said.

       Despite Putin’s announcement that he would raise Russia’s alert level for nuclear weapons, Haines said the U.S. has not observed unusual changes in Russia’s nuclear force posture.

       Haines said it is “unclear at this stage” whether Russia will try to conquer all of Ukraine, something that would require more resources than Putin has committed.