Sicilian Defense: Moscow Variation

Common Lines in the Sicilian Defense Chess Opening

Sicilian Defence: 1.e4 c5 in Chess Openings by Tim Sawyer

Sicilian Defense: Old Sicilian Variation - Chess Openings

Sicilian Defense: Old Sicilian Variation, 0-1

Sicilian Defense: Hyperaccelerated old variation : r/lichess

Vidit Gujrathi - When I was 12 years old, I developed a liking towards the Classical Variation of the Sicilian Defense. (1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5. Nc3 Nc6!).

Why would White play 2.a3 as their 2nd move in the Sicilian Defense? It's not an accepted opening and I see no benefits. How would you go about strategizing a reply, as

Encyclopaedia: Modern Chess Opening - Sicilian Defence by Alexander Kalinin (editor) - First - 1996 - from The Book Collector ABAA, ILAB, TBA (SKU: BSC0444)

Chess - The Sicilian Defence

The Sicilian with . . . Qb6 / Dynamic surprise weapons, AND A SECOND BOOK, play 1e4 e5! / a complete repertoire for Black in the Open Games, AND A THIRD BOOK