Croatia has started building a controversial coastal bridge that will allow motorists to skirt Bosnian territory - despite Bosnian objections.
Croatia hopes the bridge will ease access to Dubrovnik
The Peljesac bridge is meant to provide a continuous route through Croatia to the Adriatic resort of Dubrovnik.
Motorists currently have to go through border crossings on a 10km (six-mile) strip belonging to Bosnia-Hercegovina.
Bosnian officials say the bridge might violate Bosnian territorial waters and have threatened a lawsuit.
A statement from Bosnian presidency member Haris Silajdzic said "Bosnia-Hercegovina is not opposed to Croatia's sovereign right to link up parts of its territory, but it cannot do so in ways that infringe upon the rights and interests of Bosnia-Hercegovina".
Croatia's Prime Minister Ivo Sanader dismissed the Bosnian complaints as construction started on Wednesday.
"The span between the piers and the height of the future bridge show that Croatia has honoured Bosnia-Hercegovina's right to access its waters," he said.
But Croatian President Stjepan Mesic called for total transparency in the project, warning that the worst scenario would be for bridge-building to start and then be halted because of a dispute.
He said any difficulties with Bosnia-Hercegovina over the project must be ironed out.
The bridge, expected to be completed in four years' time, will be 2.4km long.