Greek banks : What role for banking union ?

Although Greek Prime Minister Alexis Tsipras declared on 28 June that "the deposits of citizens in Greek banks" were absolutely guaranteed, the fact remains: his announcement that the country's banks would remain closed and that the circulation of capital would be controlled has without doubt intensified uncertainties and fears.  In the context of the Greek crisis, what is it that the banking union could - or could not - do, which was created in response to the financial crisis to…