From the 'Stone Age' to the 'Destruction of the Islamic Republic'; Are Trump's Threats Displays of Power or Tools of Pressure?

In these threatening statements, Donald Trump has sometimes spoken of the destruction of a country, at times addressed a civilization, and on other occasions targeted a government. The difference can change the meaning, scope, and consequences of such threats. However, aside from these differences, the main question is: What historical precedent does the use of the language of 'destruction' have in international politics? What message does Trump convey with such threats, and to what extent does international law impose boundaries and limitations on threatening other countries?