Thursday in Cairo, President Obama underscored his desire to 'move forward without preconditions' and negotiate with Iran 'on the basis of mutual respect.' So far, no takers from Tehran. But even if there were, the bottom line is that whether it's Iran, North Korea or the Israeli-Palestinian peace process, there has been little to show for years of jawboning. Worse, the history of such negotiations should give pause to the public and to Congress. Too often, U.S. negotiators have become unwitting advocates for their adversaries, getting so caught up in the negotiating process that they cannot countenance its collapse -- or their own failure -- even in the face of undeniable evidence that the discussions are not succeeding. Consider the task of Dennis Ross, Obama's 'special adviser for the Persian Gulf and Southwest Asia.' From 1993 to 2000, as President Bill Clinton's 'special Middle East coordinator,' Ross brought enthusiasm and deep knowledge to the job. But the peace process he hoped to facilitate was constrained by U.S. laws that reasonably required the Palestine Liberation Organization to abandon terrorism and to recognize Israel before receiving aid from the United States. The PLO took tentative, initial steps toward recognizing Israel -- but followed those steps with terrorist recidivism. Yasser Arafat and Co. simply could not do one without the other. Why? Arafat's rule was legitimated among Palestinians and in the region only when the PLO was seen as being at war with Israel. The PLO's terrorist acts should have brought an immediate end to U.S. assistance, but instead they brought Ross to Capitol Hill in an effort to control the damage. An unlikely advocate for the PLO, Ross tried in numerous closed briefings to put the Palestinians' actions in context, explaining that while Arafat was head of the PLO, he wasn't directly involved in terrorism, and noting that the Palestinian Authority had condemned the atrocities. After years of this painful exercise, which was greeted with increasing bipartisan skepticism, Ross abandoned Hill briefings. To be fair, Ross's aim was to draw the Palestinians closer to an agreement with Israel that would, theoretically, obviate the need for suicide bombers, rocket attacks and snipers. In turn, the Israeli crackdowns and closures that resulted from Palestinian violations of their commitments made U.S. aid more critical to keeping the process going -- or so it was argued. But the process had become a trap, and to perpetuate it, the Clinton administration needed to obfuscate the truth about Palestinian violations of U.S. law. The more it fudged, the more difficult it became to deliver a credible message about the perils of terrorism to the Palestinians. As Ross noted in 'The Missing Peace,' his memoir of those years: 'Too often we shied away from putting the onus on one side or the other because we feared we would disrupt a process that had great promise.' But the Clinton officials didn't just shy away, they covered up: 'The security breaches, especially the releases from jail of those involved in terrorist activities, were handled in private for fear of giving those in the U.S. Congress and in Israel who sought to break ties with the PLO a basis on which to do so,' he wrote. Both the Clinton administration and that of George W. Bush fell into the same negotiating trap with North Korea. The Clinton team was so wedded to the prospect of a nuclear-free North Korea that the president and secretary of state were willing to ignore intelligence indicating that Pyongyang was cheating on its agreement. When evidence surfaced that North Korea was diverting fuel-oil shipments to military industries in contravention of the Agreed Framework, Robert Gallucci, the agreement's negotiator, blamed the Pentagon for having insisted on such restrictions. The Bush administration was little better. Indeed, Bush's North Korea envoy, Christopher Hill, came to personify negotiator's Stockholm syndrome, reportedly demanding that intelligence regarding North Korean noncompliance with its denuclearization commitments be vetted through him and cutting off the flow of information to diplomats with contrarian views on the wisdom of his approach to Pyongyang. Last month, Obama declared that Iran has until 'the end of the year' to signal serious intent to negotiate a resolution to its nuclear program. Administration officials, optimistic that Tehran is willing to engage sincerely, have designated Ross to pursue that engagement. The administration ought to remember a simple rule: Once is a mistake, twice is a pattern, and three times is blindness. Too often U.S. negotiators are diplomatic gamblers who, in a quest for progress or a place in the history books, weaken American national security in the hope that their next throw of the dice will bring success. Some negotiators have shown themselves willing to shade the truth to Congress; others have politicized intelligence. Proponents of the negotiations game argue that entangling adversaries in a process buys time and security. But as North Korea's most recent nuclear test proves, the time that negotiations buy helps only our adversaries. The writer is vice president for foreign and defense policy studies at the American Enterprise Institute. 