At noon AEST on Thursday, the benchmark S&P/ASX200 index was up 8.1 points, or 0.1 per cent, to 8,206.3, while the All Ordinaries had gained 6.4 points, or 0.08 per cent, to 8,476.3.
Pepperstone head of research Chris Weston said while President Joe Biden was reportedly attempting to deter Israel from targeting Iranian bases, the geopolitical headline risk remained firmly entrenched and traders were watching closely.
An Israeli response might not come until after the Rosh Hashanah holiday ends at sundown on Friday, observers suggested.
Seven of the ASX's 11 sectors were lower at midday, with industrials, tech, telecommunications and property higher.
The real estate sector was the biggest mover, up 1.2 per cent.
Stockland had advanced 1.7 per cent, Goodman Group had gained 1.2 per cent and Mirvac was up 2.3 per cent.
In the heavyweight mining sector, gold miners were lower as the price of the precious metal fell slightly to $US2,656 an ounce.
Evolution had dropped 1.1 per cent, Northern Star had slipped 1.6 per cent and West African Resources had fallen 2.1 per cent.
Elsewhere in the sector, BHP was up 0.6 per cent, Fortescue had climbed 0.3 per cent and Rio Tinto was basically flat.
The big four banks were mixed, with CBA up 0.5 per cent and NAB adding 0.2 per cent, while Westpac had dropped 1.1 per cent and ANZ had dipped 0.3 per cent.
The Australian dollar had dropped to 68.68 US cents, from 68.95 US cents at Wednesday's ASX close.
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