"I said, '(Nuclear weapons are) not a problem. We've already taken the nuclear weapons out. There's none there. We're not gonna put them back in,'" Biden responded, without provided the date when such a conversation had occurred.The U.S. president further criticized Putin's ambitions: "All he wants to do is re-establish the Warsaw Pact. I can't let that happen. This guy is not a good guy."These discussions reflect long-standing tensions over Ukraine's security, which were central to the 1994 Budapest Memorandum. Under the agreement, Ukraine relinquished its nuclear arsenal — the world's third-largest — in exchange for assurances from the U.S., U.K., and Russia not to use force or economic coercion against Ukraine. Despite these commitments, Russia launched a war against Ukraine and has repeatedly issued nuclear threats against Ukraine and its allies.