US Secretary of State Marco Rubio said there are “some good signs” that an agreement between Washington and Tehran could be reached, while cautioning against excessive optimism.

Speaking to journalists, Rubio said Pakistani officials are expected to travel to Tehran on Thursday, expressing hope that the visit could help move the process forward, The Caspian Post reports, citing Al Jazeera.

“The president’s preference is to do a good deal, that’s his preference. It’s always been his preference. If we can get a good deal done, that would be great,” Rubio stated.

He added that if negotiations fail to produce a satisfactory agreement, US President Donald Trump has alternative options available.

“But if we can’t get a good deal, the president has been clear - he has other options. I’m not going to elaborate on what those are, but everybody knows what those are,” Rubio said.

The top US diplomat also stressed that while there are encouraging developments, he remains cautious about the outcome.

“There are some good signs, but … I don’t want to be overly optimistic, as well, so let’s see what happens over the next few days,” he added.