I believe Bosnia aspires to join the EU in the future, so the EU should have some leverage to require Bosnia to cooperate in eradicating any ISIS bases.
The EU won't have the guts. Plus the Saudis will make sure they won't.
The EU turns a blind eye to Muslim supremacists in every country in Europe and backed Izetbegovic and his Islamists in the 1990’s (along with NATO and the US).
Maybe they should have such leverage, but they won’t use it because it’s not politically correct.