They are both members of a secret society at Yale University where they most likely attended together, Kerry being three years older and university in America usually lasting four years. The society called "skull and bones" is affiliated with the practice of masonry. This means that they have likely
known each other for 40 years.
The Bulgarian authorities made a stupid and absurd decision when they did not let a government flight with official representative of the Russian Ministry of Foreign Affairs Maria Zakharova on board fly to North Macedonia