Well, let's say all the Syrian weapons are destroyed by perfect strikes that don't harm any living being. They will just buy more.
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http://www.cnn.com/2013/08/28/world/meast/syria-how-did-we-get-here?c=&page=5
"Russia and Syria are longtime allies. For one, just take a look at their weapons deals. Between 2007 and 2010, Russian firms selling weapons to Syria made almost $5 billion.
It would be costly for Russia to end that relationship, analyst Peter Fragiskatos said this year. "Russia's leadership still sees much to lose economically and strategically from cutting Syria loose," Fragiskatos wrote. "Russia sees Syria as another test case for the West's appetite for intervention and views the danger of U.S. involvement as a direct threat to its own interests."
There are other reasons to suspect that Russia will keep supporting Syria. Russia's only naval base in the Mediterranean is on the Syrian coast, and Putin is still upset about NATO's bombing in Libya two years ago that removed Russian ally Moammar Gadhafi from power."