Short answer
Make every commitment visible, give it one owner and a date, and review the list together every week or two. Accountability takes hold when peers hold each other to account, not only when the CEO does. That takes a team that’s comfortable saying “you said you’d do this, and it’s not done” to each other without it turning personal.
The longer answer
Many leadership teams treat accountability as the boss’s job. Each leader reports up, nobody reports across, and problems between functions go unspoken until they’re expensive.
Two habits change that. First, a shared list of commitments the whole team can see. Second, practice at the hard conversation: raising a missed commitment early, directly and without blame. Both can be learned, and once the senior team does them, managers start doing them too.