The problem is that some people don't know where the time for diplomacy ends and the time for direct action begins.
Kerry, when talking about how he would handle the Iran situation during the debates talked about inposing sanctions, then offering some deals, then applying some pressure, then this, then that.
In the mean time Iran continues developing and building their weapons. What happens when they drop a nuclear warhead in the middle of Tel Aviv?
A reactive posture when dealing with terrorists resulted in 3000 deaths on 9/11. We must allow not ourselves to return to those times.
And when it comes to our "allies," several have stated that, regardless of who is in power after this election, they will not provide any support. Diplomacy will do nothing for these countries.
And, after what Kerry said about our current Iraq allies, about them "being the bribed and coersed", a Kerry win could result in lost credibility with these countries.
In the end, as a worst-case scenario, we fail to gain the allies Kerry wants and we lose the allies we have, placing us in a worse situation than we are in now.
Although, why on Earth you want France for anything is beyond me. We all know from past experiences that the only things they're good at is insulting Americans and waving white flags.