He is not in a position to negotiate any "security agreement". The United States is unable to provide any real security agreement to a government that is quite obviously not interested in any real, lasting peace, one that sought repeatedly to drag us and Europe into WW3. Doing so is an open invitation to try and re-litigate the conflict (which the US/Nuland/USAID _created_ in 2013) a few years from now, this time with you and I in the trenches. "Soft" security guarantees, by establishing significant US interest in Ukraine's "minerals" (ephemeral though they may be), and therefore presence on the ground, was on the table, but Zelensky misread that as a robbery.
Emotional thinking and platitudes about "bullies" are not really applicable here. You have to think about the eventualities that we could be affected by if things go sideways, and with the current set of characters in Ukraine, they most definitely will, and soon.
There's that emotional thinking again. _We_ started that war when we funded a coup there in 2013 and hand-picked[1] their rabidly anti-Russian government. We also funded and condoned their neo-Nazis, without whom none of this would work [2]. Mostly Russian-speaking Eastern Ukraine disagreed with that kind of thing. After all, it was mostly them who elected the president that we overthrew. West Ukraine started shelling east trying to subdue them, calling it an "anti-terror operation". Russia provided "lethal aid". Things escalated. The conflict did not start in 2022. Suggesting that we can just go ahead and build tactical nuke bases right next to where ~70% of Russia's population lives, and Russia should just roll over and let it happen, is idiotic and reckless.
As if Trump and Vance's demand that Zelensky abase himself in front of them isn't "emotional thinking"; as if cutting off military aid because Zelensky didn't bow and scrape isn't "emotional thinking".
As if taking the hundreds of nuclear red lines Putin has laid down and allowed to be crossed without a nuclear response, isn't "emotional thinking".
Emotional thinking and platitudes about "bullies" are not really applicable here. You have to think about the eventualities that we could be affected by if things go sideways, and with the current set of characters in Ukraine, they most definitely will, and soon.