Which country has used maximum veto power?

Russia

Explanation:

Russia Countries that have vetoed the most in the UN Security Council include Russia, the United States, and the United Kingdom

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".