President-elect Joe Biden "believes that if Iran comes back into compliance, we would too," Blinken told his confirmation hearing before the Senate Foreign Relations Committee.

"But we would use that as a platform with our allies and partners, who would once again be on the same side with us, to seek a longer and stronger agreement," he said.

A new agreement could address Iran's "destabilizing activities" in the region as well as its missiles.

"Having said that, I think we're a long way from there," Blinken said, adding that he would watch for Iran's next steps.

Outgoing president Donald Trump bolted from an agreement negotiated under his predecessor Barack Obama under which Iran was promised sanctions relief in return for scaling back its nuclear program dramatically.

Blinken said that the agreement had been succeeding, pointing to assessments that Iran was now three to four months away from enough material for a nuclear bomb, as opposed to more than a year earlier.