Trump has to threaten complete annihilation to deter Iran. If Iran actually attacks American assets, the American President will be obliged to retaliate. No American President will survive if American assets are attacked and he doesn’t do anything.
Trump doesn’t want a war with Iran. He is against regime change. Trump didn’t do anything when Iran shot down an American drone and was criticised by his own supporters for being so weak. Iran pushed Trump into a corner by attacking the US embassy. He had to respond to that.
Now he realises Iran will attack American assets and he is using extreme language to deter Iran.
He used extreme language against North Korea after they launched missiles close to Japan. Then he met Kim Jong Un.
Trump’s tweet about “Iran has never won a war, but never lost a negotiation” was him telling Iran don’t get into war with him, but get into a negotiation. He has said before he is willing to meet Iran without preconditions.
Trump is a deal maker, not an ideological guy. Doing deals was what he did before he became President. He wants a deal with Iran, North Korea, China trade.