A toy can become a valuable resource, and a dog may guard it from another dog. A freeze, a fixed stare or a growl is information: one dog needs more space. Waiting to see whether the puppy gets the message risks a fight. Punishing the warning doesn't make the dogs feel safer.
Give each dog a chew without an audience
For now, put a door or sturdy gate between the dogs before you hand out chews or other prized items. Let each finish in peace. Pick up the items before bringing them back together. If they begin hovering over each other's ordinary toys, put those away during shared time too. Two identical toys won't solve it if the puppy wants the one the older dog is holding.
Don't reach between dogs to retrieve a toy or try to prove that either dog must surrender it. If one has a dangerous object, separate them safely and ask your vet or a qualified professional for help with a plan. If there has been a bite, fight or repeated snap, keep them separated around resources and get individual behavior help. If the older dog's tolerance has changed suddenly, a vet check matters too.
Teach a better exit before they need one
Away from prized objects, practice calling the puppy away from the older dog and rewarding that choice. Start when both are relaxed and there's room to move. This isn't a test beside the older dog's chew. The older dog deserves uninterrupted rest, the puppy can learn that coming away pays without a confrontation.
Tonight, choose two separate spaces for chew time. Set the boundary before either dog gets the toy, and pick up both chews before you open it again. That small change prevents another close call while you work out whether you need professional help.
If you want a starting point tailored to the situation, describe each dog's behavior in the AI trainer. For fighting or biting, keep the dogs safe and seek qualified help rather than testing another meeting. For more on introducing two dogs and managing shared space, see the second-dog household guide, keep valuable toys separate while guarding is possible
Sources: ASPCA on resource guarding. VCA on introducing a new dog.