Stronger US action will simply invite stronger reaction from those who wish to remove the US stranglehold of the Middle East. Sooner the Yanks go home, sooner peace will arrive. Not rocket science really is it?
These Sunni IS people have to be supported by the Yanks. After all it was the Yanks and the Israelis who trained them and armed them under the FSA when they attacked Syria.
It is not that hard to show how the two bombs had Yank fingerprints al over them.