Pakistan's former army chief, Gen. Raheel Sharif finally arrived in Riyadh to start his new mission as head of the Saudi-led Islamic military alliance to face terrorism. According to security and intelligence experts, the Saudi-led 39 coalition seeks to reign in Iranian expansion in the Arab world as well as the threats from the so-called Islamic State (IS) terror group. Iran strongly supports Shiite militias in Iraq, Yemen, Syria and Lebanon as well as fueling violence against Saudi police personnel in eastern the neighboring kingdom. The Sunni coalition, that is widely known in the Arab media as ‘Muslim Nato' was launched by Riyadh in 2015. It considers Iran and its leader Khamenei as a major threat to the whole Middle East. Pakistani Defense Minister Khawaja Mohammed Asif, confirmed Islamabad had issued a No-Objection Certificate for the veteran general to assume command of the coalition after reaching an understanding with Riyadh on the matter. Talks on Sharif appointment began after he stepped down from his Pakistani post in November. Sharif was nominated for the highly important post for his distinguished character and great military capabilities, Pakistani military sources said. He was the 15th Chief of Army Staff of the Pakistan Army from 2013 until his retirement in 2016. The Pakistani army is one of the largest and most professional forces in the Islamic world. Asif described Sharif as a professional military with positive and balanced views who never showed political ambitions during his military service. As Inspector General for Training and Evaluation in the Pakistani army, he enhanced the military colleges in the country and provided unconventional warfare training to the troops. Sharif has a long experience in combating terrorism. Observers say he has changed the army's focus more towards carrying out counter-insurgency operations against Taliban offshoot in Pakistan. On Tuesday, Iran announced reservations on the appointment of Sharif, claiming the move could disturb unity among Muslim nations. Iranian ambassador to Pakistan, Mehdi Honardoost was quoted as saying that Tehran had conveyed its concerns to Islamabad, according to Pakistani media outlets. "We are concerned about this issue... that it may impact the unity of Islamic countries," Honardoost said, according to Hindustan News. "But that does not indicate that Iran is satisfied with this decision or it has accepted the same," Dawn newspaper quoted the envoy as saying.