I suspect you're joking, but an actual ICBM attack would have likely struck before the false alarm message was issued.

There was a 38 minute delay before the false alarm message: https://www.washingtonpost.com/news/posteverything/wp/2018/0...

Meanwhile an ICBM would likely impact less than 35 minutes after launch: https://en.wikipedia.org/wiki/Intercontinental_ballistic_mis...