Mattis considered the bombing plot intended to kill the Saudi ambassador to the U.S. to be an act of war, but the Obama administration did nothing because it was negotiating with Iran to get the (awful) nuclear deal (tip to Instapundit).
When the first news came out I immediately thought it was an Iranian act of war that required a serious military response:
If Iran was plotting to blow up embassies in Washington, D.C., as the news is indicating, we should declare war on Iran. Period. They've been at war with us for over thirty years and it is time we took notice.
The form of the war is up for debate, but war really is the answer to war.
As it turned out it was a plot to blow up an American restaurant in Washington, D.C. in order to kill the Saudi ambassador.
But the administration treated it as a "whatever" moment. Instead of waging war on Iran in return, excuses were made.
Given that Obama was willing to look away from an act of war (and this) in order to get the nuclear deal with those nutballs, do you really think that the Iranians thought that Obama would ever try to enforce the weak provisions of the deal?
Iran's actions since the 2015 deal demonstrate the contempt they have had for Obama's confidence that he could reset Iran into a successful regional power that respects international norms.
Smart Diplomacy, indeed.