and a true was nowhere joined now by marianna pl chair, and she's senior research associate at the harvard kennedy school. mariana, welcome. what should we make of lot of importance, latest comments on russia using nuclear weapons as well. steven, this is the latest instance of the long string of nuclear rhetoric and signaling that has been coming out of moscow since the beginning of this full scale invasion . this was significant. we knew that the russian leadership has been reviewing their military nuclear doctrine. and the general expectation has been that the russian threshold for the use of nuclear weapons will be lowered. there's been a lot of talk about this by russian liter, inspired by russian commentators. and so here we have a preview, right? there are a few significant things to note. one is the previous version of the russian doctrine adopted in 2020 allowed, also receive a new response to a large scale conventional attack, but only in extreme circumstances where this, the very survival of the state a was at stake. now we, we understand from mr. perkins, speech today, this for