Syria has shown no respect for others borders. When they had the Golan Heights they were constantly shooting at Israeli Farmers. The occupation of Lebanon and encouragement of Hezbollah's incursion's into Israel. The Black September invasion of Jordanian territory by the Syrian army. Syria needs to be held in check. Israeli overflights remind Syria that they can not practice state terrorism with out consequences. The missle sales inhibit these reminders but may provide for greater instability in the region by making more serious gestures the only Israeli option.
UN chief condemns Palestinian toddler killing, urges calm (Reuters)
from the article: Sharon: Russian missiles being sold to Syria do threaten Israel