From what I've read & seen, there was no concrete evidence that they were restarting their nuclear program.
Here's the deal with war: we have had quite a few of them since WWII. Very few of them have gone as expected. Most have turned into a quagmire w/ no clear definition of victory, and most have led to unexpected negative consequences, many civilian deaths & much more prolonged engagement than what was originally forecast.
War is to be avoided at ALL COSTS. The measure for engagement should always be "is there an immediate threat to the security of the homeland, and are there any other options?"
WAR IS A LAST RESORT. ALWAYS.