The US ambassador to Pakistan, Cameron Munter, is to step down this summer after serving less than two years in the job, a US official said Tuesday. Munter has been Washington\'s man on the diplomatic frontline at a time when relations between the two countries have dramatically worsened, especially over the covert raid that killed Osama bin Laden last May and US air strikes that killed 24 Pakistani soldiers in November. US ambassadors usually serve three-year terms, but in posts considered as tough as Pakistan, are allowed to serve two years with the option to extend for a third. The official said it was the ambassador\'s decision to go and denied a press report speculating the move was related to poor relationships with Islamabad and Washington. \"He is not being sacked, he has decided to move on,\" the official told AFP. \"He maintains good relations with both the government of Pakistan and the US government. It\'s his decision alone. There\'s no dissatisfaction with his performance from Pakistan or Washington,\" the official added. Other people close to the ambassador say he has been frustrated that the CIA and Pentagon call the shots for the United States in Pakistan, and that he feels his job has been to contain the fallout rather than set policy. Analysts were taken aback, warning his departure could complicate efforts to repair alliance with the US and reopen NATO supply lines into Afghanistan that Islamabad shut five months ago in protest at the 24 soldiers\' deaths. \"It\'s very premature. I think there must be some differences with his own government or he must have been finding it difficult to work in Pakistan,\" Pakistani political and security analyst Talat Masood told AFP. \"It\'s unfortunate because he was doing a great job in a difficult situation.\" News of Munter\'s move emerged with US Secretary of State Hillary Clinton in India, Pakistan\'s bitter rival, where she called on Islamabad to do more against Islamist militants in comments likely to antagonise Pakistan, which says it has already sacrificed more than any other nation. Munter arrived in the country in October 2010, after his predecessor Anne Patterson spent more than three years in Pakistan. The US official said the ambassador would be leaving \"this summer at the end of his two-year tenure\". In his talks in Washington, Munter has advocated doing more to repair ties with Pakistan, arguing widespread anti-US sentiment in the country is a sign not of hostility to the US but of disappointment with the results of the relationship. In Pakistan, he has been determined to improve America\'s public image, travelling widely in a bid to meet as many ordinary Pakistanis as possible. Masood said Munter had been well accepted in Pakistan, and that a change at the top of the embassy was unhelpful at a difficult time. \"It definitely comes at a bad time and is unhelpful and will make things more difficult and more complicated,\" he said.