The United States has told Pakistan it will act unilaterally if Pakistan maintains ties with the Haqqani Taliban network, U.S. and Pakistani officials said. The violent Haqqani group, which U.S. officials say enjoys safe haven in Pakistan's tribal areas, is seen as a long-time asset of Pakistan's military and intelligence service. In a sharp warning seen as an ultimatum, officials in the administration of U.S. President Barack Obama have warned Pakistan not only must cut ties but also help eliminate Haqqani's leaders, The Washington Post reported, quoting officials. The U.S. message has been communicated at high-level meetings as well as in recent public statements as a growing number of senior Obama administration officials believe the old strategy of persuasion and military aid has not helped change Pakistan's behaviour, the Post said. U.S. Defence Secretary Leon Panetta, for instance, is determined to take a new approach, officials told the Post. Panetta told reporters this week "we are going to take whatever steps are necessary to protect our forces" in Afghanistan from attacks by the Haqqani network. The network has made numerous strikes against U.S. forces and is suspected of the being behind the Sept. 13 attack on the U.S. Embassy in Kabul. Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, met Friday with Pakistan's army chief. The Post said the focus of their talks was the "proxy connection" between Pakistani intelligence and the Haqqani network. U.S. Secretary of State Hillary Clinton, in her 3 1/2-hour meeting Sunday in New York with the Pakistani foreign minister, warned Pakistan is fast losing friends in Washington, the Post reported, citing an official familiar with the talks. "We are expressing the firm conviction that things have to change ... in Miranshah (in Pakistan's North Waziristan where the Haqqanis are based) and in Islamabad, as well," another official was quoted as saying. The official said with Pakistani cooperation, "we know that there are ways to get at extremist leaders anywhere." U.S. Ambassador Cameron Munter said in a radio interview in Islamabad last weekend the United States has evidence "linking the Haqqani network to the Pakistan government."The Post said Munter's message had been approved at senior levels in Washington.