U.S. Secretary of State Marco Rubio said Friday there was "slight progress" during talks with Iran amid uncertainty as to whether a deal will be reached or war will resume.

He spoke days after U.S. President Donald Trump said he was holding off on a military strike on Iran because "serious negotiations" were underway. Trump has been threatening for weeks that the ceasefire reached in mid-April could end if Iran does not make a deal, with shifting parameters for striking such an agreement.