US President Donald Trump hinted on Sunday that a completed agreement with Iran was close, but then backed down slightly and indicated that there was still some way to go.
Despite the fluctuations, the cheerful mood on the stock markets looks set to persist during the initial Monday trading session.
Japan's Nikkei 225 is up 2.9 percent at lunchtime and the broader Topix is up 1.2 percent.
In China, Shenzhen rose by 1.0 percent and Shanghai by 0.8 percent.
The Kospi is also climbing, up 0.4 percent.
The Hong Kong-based Hang Seng is also up 0.9 percent.
