WASHINGTON (Reuters) - A weekend tiff involving lawmakers from Pakistans tribal areas and airport security personnel in the United States underscores how tough it is to reverse years of US-Pakistani mistrust. The six lawmakers were en route from Washington to New Orleans on Saturday when two were tagged for further screening at the capitals airport - scrutiny they found insulting. They scrapped their two-week US trip, which was sponsored by the State Department, and went home midway through. The airport incident was splashed across Pakistani media on their return, with the parliamentarians claiming they were told they would not be subject to full-body electronic scans. Washington says those assurances were not given. This situation could have been avoided, said an official at the Pakistani Embassy in Washington. State Department spokesman PJ Crowley said he regretted how the procedures were perceived by the lawmakers. A US airport security official said the measures were an essential part of the multilayered approach to keep the public safe. Either way, the outcome was embarrassing for the Obama administration and feeds into a pattern of Pakistani hostility and suspicions over US intentions in the region. We are genuinely trying to improve relations but it doesnt mean there will not be misunderstandings along the way, said Larry Schwartz, a senior spokesman for the US Embassy in Islamabad, who accompanied the parliamentarians. While in Washington, the group met State Department officials, including the special representative to Afghanistan and Pakistan Richard Holbrooke, as well as members of Congress. The programme is one of many by the United States to boost people-to-people ties but the discordant ending to the visit underlines how hard it is to reach that goal. It is impossible to characterise the US-Pakistan relationship both historically and today in anything but the most complex and contradictory terms, said Alexander Thier from the US Institute of Peace. Behaviour on both sides is duplicitous. The Pakistanis do not feel they are equal or respected partners by the United States. They feel mistreated. The trust deficit, said former US ambassador to Pakistan Wendy Chamberlin, is one of the chief obstacles to improvements in the relationship. The majority of Pakistanis distrust the United States because they believe we favour military dictators over civilian leaders and we are quick to abandon economic aid once we have achieved our security goals, she said. There have been signs recently of better understanding, with Washington praising Pakistan after the arrest in Karachi of a top Afghan Taliban commander, Mullah Abdul Ghani Baradar.