May 29 (UPI) -- U.S. Vice President JD Vance said the United States and Iran were very close to finalizing a 60-day memorandum of understanding to extend their cease-fire and while they were "not there yet," Washington was well placed to check Iran's ability to develop a nuclear weapon. "There are a couple of issues on the nuclear stuff, the highly enriched stockpile and also the question of enrichment. We do think they're negotiating, at least so far, in good faith , and we're making some