"We thought the US Secretary of State could make a verbal binding agreement on behalf of all of NATO" is simply absurd. Treaties exist for a reason; hell, a verbal contract isn't legally valid in the US for a $1,000 purchase, let alone to commit 30 countries' foreign policy.
Incidentally, if someone’s breaking agreements, it’s Russia. They wrote down an actual promise to not invade Ukraine. https://en.wikipedia.org/wiki/Budapest_Memorandum_on_Securit...