We saw this quite recently in the case of Saddam Hussain & in the case of Osama bin Laden. Earlier, the same happened with Gen. Zia ul Haq, the former president of Pakistan. The case of Shah e Iran was no different. After taking full advantage of them, the US used them as scapegoats to cover their failure.
Now in the aftermaths of the Afghan war, the US is finding another scapegoat and this seems to be Pakistan. By blaming the links of Haqqani network with Pakistan, they simply want to blame us for what they have failed to achieve in Afghanistan. In reality Haqqani network is no different from Osama Bin Laden or Saddam Hussain used by US in different times.
Let us consider each of them separately:
Saddam Hussain had been America's blue-eyed - clearly evident from the" neutrality” America acquired during Iran-Iraq war. In 1979, after Khomeni revolution a number of diplomatic hostages of the US were held by Iran. Carter’s administration also wanted to seize control of the oil fields in Iran and they could not have done this by their own marines because this would mean stimulating the Soviet Union to act under UN charter and stop America's progress. So, they looked towards Saddam who seemed to be pleased with this support.
An article written by Francis A. Boyle published in the Washington Post in February 1986 suggested Read more at "The Absolute Verdict"