(CNN) -- In his speech about Syria Tuesday night, President Obama tried to make a graceful turn on a fast-moving platform. He wanted to explain to a skeptical public why they should support his plan for a limited military attack on Syria in response to, the administration says, the use of chemical weapons by the Syrian President Bashar al-Assad. But his effort was only mildly successful, restating arguments that will be familiar even to those who have not been paying close attention, but also shining a spotlight on the weaknesses of the administration's case. In the 36 hours leading up to his speech, the circumstances that would determine that case took several confusing turns. Suddenly, with Syria's expressed willingness to give up its chemical weapons, a possible diplomatic avenue opened up that might allow the president to claim victory without launching a single missile. But this plan is far from a sure bet and brings problems of its own. This made the president's job of persuasion even more difficult.
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Frida Ghitis: Obama went into speech with Syria situation in new flux; was mildly successful
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She says he saved talk of diplomatic plan till after he described gassing of kids
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She says this because clearing Syria's chemical weapons could fall through, as Assad buys time
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Ghitis: If diplomacy restores "red line," Obama's threat will show threat of consequences matters
Whatever happens next, there is no question that the suffering of the Syrian people will not end any time soon and that Syria will continue to be a daunting problem for President @placeholder.