Stressing Frank's engagement in developing the US-Croatia relation, Mesic said Frank was a very fair interpreter of the US policy in Zagreb, adding that the US diplomat also informed Washington of Croatia's political positions.
The US-Croatia relations today are stronger than ever, the US ambassador said.
He underlined Mesic's efforts invested in righting the wrongs from the past and normalising relations between Croatia and Serbia.
Mesic bestowed a high state decoration on Frank for his contribution to the development of US-Croatia relation, the statement said.
Frank will be replaced by Robert Anthony Bradtke.