Former interior minister Chaudhry Nisar Ali Khan Monday penned down a farewell letter to the Secretary of Ministry of Interior, praising his services. He termed his recent tenure as the toughest of thirty years political career. The ex-interior minister praised Arif Ahmed Khan for his resilience since the very start. Ch Nisar said that the present tenure was the most challenging in his entire political career of over 30 years in which he led various ministries. The main challenges that the ministry faced included militancy, national security, maintenance of law and order, and constituting new policies. He expressed confidence in senior bureaucracy and hoped for further improvement in the output of the ministry.