I'm not him, but the Manhatten project cost ~$25 billion dollars and didn't have access to today's physics knowledge or computer-aided design capabilities. The

I'm not him, but the Manhatten project cost ~$25 billion dollars and didn't have access to today's physics knowledge or computer-aided design capabilities. There are a lot of countries that can match $25 billion in expenditure - Musk spent almost twice that on Twitter - and the real cost is probably lower. We've also got a lower-bound on the difficulty of producing missiles based on what North Korea can do.