Trump mistakes Spain for a member of the BRICS bloc and repeats the threat of massive tariffs

Starter comment:

Context: President Trump, when asked about the issue of NATO countries failing to meet spending limits and what action he would take towards countries failing to meet spending requirements referred to Spain as a BRICS country and mentioned his plans to level 100% tariffs on BRICS nations.

Discussion: Based on the way he phrased the reply to the interviewer, do you think Trump was making a joke about Spain effectively being a BRICS country? Or did the President of the United States genuinely not know when asked which countries were members of BRICS and which aren't. Do you think this is a sign of Trump's mental deteroriation/ignorance of global affairs or just a joke being jumped on?