US Secretary of State Marco Rubio said negotiations with Iran aimed at reopening the Strait of Hormuz have made progress. Rubio made the comments on Tuesday, but did not disclose the nature of the progress or provide details about any potential agreement.

He spoke during a ceremony to sign a memorandum of understanding on nuclear cooperation with Paraguayan Foreign Minister Ruben Ramirez Lezcano. Rubio did not identify other parties involved in the discussions or give a timetable for the talks.

The secretary of state’s remarks signaled US optimism about the effort to reopen the Strait of Hormuz. The available information did not explain which issues had advanced, whether a settlement was nearing, or what further steps might follow in the negotiations.