While a potential deal with Iran marks a diplomatic win for President Trump, experts warn that fragile details and regional instability could threaten its success.

The announcement of an impending Iran deal could not have been a better birthday gift for President Donald Trump – but celebrations could be short-lived if fragile details of the agreement fail to hold. Obstacles will not be easy to overcome, Chinese observers say. Any lasting framework must navigate uncertainties around the fate of Iran’s nuclear programme under its new regime, the mechanisms of sanction relief for Tehran and a rattled Israel, which has vowed to remove what Prime Minister...