TEHRAN — Iran’s supreme leader on Thursday challenged two of the United States’ bedrock principles in the nuclear negotiations, declaring that all economic sanctions would have to be lifted on the day any final agreement was signed and that military sites would be strictly off limits to foreign inspectors.

The assertions by the leader, Ayatollah Ali Khamenei, could be tactical, intended to give both the negotiators and himself some political space to get Iran’s hard-liners accustomed to the framework of the nuclear deal reached a week ago with the United States and other world powers.

But they sharply illustrated the difficult hurdles that lie ahead as Secretary of State John Kerry and a large team of diplomats, energy experts and intelligence officials try to reach a June 30 deadline that would ensure that Iran could not race for a bomb for at least a decade — and would establish a permanent inspection regime to catch any cheating.

In his remarks, Ayatollah Khamenei added several stinging criticisms of Iran’s regional competitor, Saudi Arabia — calling its new leaders “inexperienced youths” — a sign of rising regional tensions that could pose another threat to the negotiations, even as diplomats strive to keep the issues on separate tracks.