A senior diplomat says Tehran rejected a US request for help in fighting terrorist groups because of Washington’s lack of sincerity. “The US asked Iran for help in the fight against terrorism. However, we believe the US lacks sincerity as some of these terrorist groups are simultaneously supported by the US,” Press TV quoted Deputy Foreign Minister Hossein Amir Abdollahian as saying on Tuesday. The presence of foreign military troops in the region over the recent years has shown that having a military approach toward undeveloped countries not only fails to solve the issues of terrorism and instability, but may even exacerbate the problems, he added.