Interim U.S.-Iran deal faces uncertainty as Lebanon fighting continues and talks move to Switzerland

Why are world leaders still cautious about the deal?

Sources say the agreement is preliminary and leaves major details for later negotiations, including questions about Iran's nuclear program; one report also says it does not address Iran's missile program or regional role NYT,NDTV. Continued fighting in Lebanon has added to doubts about whether the agreement can hold Hindu,BBC.

What does Lebanon have to do with the U.S.-Iran agreement?

The deal was described as covering an end to hostilities on multiple fronts, including Lebanon, so renewed fighting between Israel and Hezbollah has been treated by mediators and officials as a threat to the broader agreement NYT,Aol,Guardian.

Why is the Strait of Hormuz central to this story?

The strait is a major shipping route for oil and liquefied natural gas, and the interim deal included reopening or keeping it open BBC,Hindu. Iran later said it had closed the waterway again over the Lebanon fighting, while the U.S. said traffic was still flowing BBC,News18.