Delhi Chief Minister Arvind Kejriwal has been faulted for "inappropriate" references to the Prime Minister in a letter sent to him today by Lieutenant Governor Najeeb Jung.That line will undoubtedly add to Mr Kejriwal's charge that Mr Jung is committed to helping the PM run Delhi by proxy.Trading charges in letters written to each other and released to the media has become the stock-in-trade for the Lieutenant Governor and Mr Kejriwal, who both claim the right to decide key appointments for Delhi. The Centre has backed the Lieutenant Governor; Mr Kejriwal has challenged that submission in court, where his case is being reviewed. They are currently warring over Mr Kejriwal's choice of chief for the Delhi Commission of Women, Swati Mahilwal. Mr Jung has today refused to sign off on her nomination, citing a technicality.During his first term as Chief Minister in 2013, Mr Kejriwal chafed with the Lieutenant Governor over the latter's alleged bias towards the BJP. In February this year, when Mr Kejriwal returned for a second term with a gigantic victory, their skirmishing turned meta.In an apparent acknowledgement of this, Mr Jung writes today, "You and I should not look back at this moment when you have won such a massive mandate, and see it as a wasted opportunity..."The Lieutenant Governor earlier this week astounded many by declaring in a note that his office equals the government of Delhi, drawing a sharp response - also in writing - in which Mr Kejriwal pointed out that he is the elected leader of Delhi and that Mr Jung works as the "puppet" of the PM.Mr Jung said in his new note today that it was "not the intent of this office to negate the position" of Mr Kejriwal and that he was merely pointing out that he functions as the Centre's representative in Delhi, which is a union territory.However, he said, Mr Kejriwal must respect the obligation to consult him for important appointments.