I am wondering which one is correct:
- "Secessionism as a challenge of modern Europe"
- "Secessionism as a challenge to modern Europe"
Thank you! :)
Both phrases are possible.
The choice depends on the actual context.
Look at the entry from Merriam-Webster's Dictionary (https://www.merriam-webster.com/dictionary/challenge):
1: a stimulating task or problem // looking for new challenges (In this case we can use of to show the possession of the problem)
2: a calling to account or into question
a challenge to unauthorized use of public funds (In this case we use to to show the direction of the process)
Compare two examples from Reverso.context.net:
"Notwithstanding those efforts, the challenge of achieving sustainability remains".
"The situation presents a challenge to the international community, which must find effective means to combat that menace".