WASHINGTON -- US Vice President JD Vance said Wednesday that he thinks the United States is making progress in diplomatic efforts regarding the war with Iran, though the US red line on Iran's nuclear issue remains.

Vance noted that he had phone calls with US President Donald Trump's envoy Steve Witkoff and son-in-law Jared Kushner, as well as "a number of our friends in the Arab world".

"I think that we are making progress. The fundamental question is do we make enough progress that we satisfy the President's red line," Vance said, noting, "The red line is very simple. He needs to feel confident that we put a number of protections in place such that Iran will never have a nuclear weapon."

"Obviously, these negotiations are very sensitive," Vance added, "The president has set us off on the diplomatic pathway for now, and that's what I'm focused on."

Trump said Monday that the weeks-long ceasefire with Iran remains in effect but is on "massive life support", while signaling that Washington will continue pursuing diplomacy with Tehran despite his rejection of Iran's latest peace proposal.