Here's the Reuters report on it: Dozens of U.S. diplomats urge military strikes against Syria's AssadEven as a pacifist, I can tell you that from a global-chessboard mentality, you:
1) Work with Assad and Putin to defeat al Qaeda and IS in Syria and Iraq and anywhere else they pop up
2) After al Qaeda and IS are out of Syria, continue working with Assad and Putin to establish a new Syrian Constitution acceptable to the Syrian electorate and
3) Hold a free and fair Syrian presidential election in which Assad either wins or loses.
What you don't do is escalate militarily against Russia and its various allies in the conflict (Iran, Hezbollah, Iraqi Shiites, and others). There's no sense in escalating at all.
The fall of Assad by US military means would not mean a more stable, more democratic government than that which could be created while allowing Assad to run democratically to be accepted or rejected by the Syrian people (all of them).
Toppling him or insisting that he not be allowed to run are two completely undemocratic approaches either of which would only serve a destabilizing purpose conjured up by neocons and neoliberals.
All of that said, if you think Putin is some weakling who will just stand idly by while the US pounds the Syrian military, you're an ignoramus. However, it is the fact that Putin wouldn't just stand idly by that prompts neocon/neolib empire builders to risk WWIII.
You don't think Chinese troops and industrial might wouldn't throw in with Russia rather than simply wait it out only to be the next target of the neocons? Is the US pivot against China willing to bank on all the states around the South China Sea jumping in against China while Russia has its hands full all around its borders? Would they even prevail if they were to give it their all? Only China is nuclear of them.
The US would have to hit China hard and first and pray that China couldn't still retaliate, a prayer that would not be answered. US cities would be hit with nuclear warheads, millions of Americans would be incinerated, vast swaths of America would be radioactive (virtually uninhabitable), and millions more would die agonizing deaths from radiation sickness.
These so-called mid-level diplomats envision sucking Europe back into world war created by US global hegemonic designs (megalomania, frankly).
Look, the US is not as militarily powerful in the conventional sense as most Americans are led to believe. More importantly, Russia is also not going to be invaded without firing off its nuclear arms to stop the main aggressor (the US). Just as with the case with China, Russian nuclear warheads would reach US soil: major US cities. The US does not have a Star Wars shield!
So, what this is on the part of the signatories is dangerous, stupid bluster.
I would instantly terminate the State Department employment of every single one of those who signed the nonpublic "cable." We should simply not have such maniacs working at the State Department.