The UN environment chief insisted Monday that talks on a landmark plastic pollution treaty were not a failure, saying important progress was made despite negotiations collapsing without agreement.

Delegates from more than 170 countries attempting to negotiate a treaty to curb global plastic pollution ended a weeklong meeting in Busan early Monday without an agreement, pushing talks to another session next year.

Global talks to forge a landmark treaty aimed at reducing plastic pollution broke down after negotiators from more than 170 countries remained deadlocked over how to curb the world’s growing mountain of plastic waste.