I find it bigly hard to believe that Trump used the word 'plenipotentiary' let along how to pronounce it.
I had to look it up..
plen·i·po·ten·ti·ar·y
/ˌplenəpəˈtenSHərē,ˌplenəpəˈtenSHēˌerē/
noun: plenipotentiary; plural noun: plenipotentiaries
1. a person, especially a diplomat, invested with the full power of independent action on behalf of their government, typically in a foreign country.
synonyms: diplomat, dignitary, ambassador, minister, emissary, chargé d'affaires, envoy
"a plenipotentiary in Paris"
adjective: plenipotentiary
1. having full power to take independent action.
"he represented the Japanese government in Seoul as minister plenipotentiary"
.. sounds like something he would want.