June 23 (Reuters) - Wall Street's main indexes opened

subdued on Monday as investors awaited Iran's possible response

to U.S. airstrikes on its nuclear facilities over the weekend,

sparking fears of a broader conflict in the Middle East.

The Dow Jones Industrial Average fell 28.3 points, or

0.07%, at the open to 42178.55. The S&P 500 rose 1.8

points, or 0.03%, at the open to 5969.67​, while the Nasdaq

Composite dropped 20.4 points, or 0.10%, to 19427.007 at

the opening bell.