As I said, some of you Indiana really easily satisfied
You can expel anyone without giving a reason even diplomat as you are the host country, just declare that person a "persona non grata" and nothing anyone can do as bounded by Vienna convention that person had to leave
It is not the same as arresting a diplomat in public knowingly that they have diplomatic immunity and cuff her in public, then expel her from some drummed up charge (quote from Indian members here, not my word)
Indian should show some cajones and arrest one of the American diplomat and publicly humiliate him and deport him without apologising, and cancel the Apache and C-17 and P-8I contract and show that to the American, but Indian satisfied with simply "ask" one of the diplomat to leave lol
By the way, Kerry did not apologise, he expressed his regret, that's not the same as saying sorry, he'll even state department express his regret, even the Chinese in Hainan get the letter of 2 sorries....
You Indian should ask for more