Under International law the obligation of a neutral country is

Under the traditional law of neutrality (Oppenheim), a neutral State has three duties: abstention (not helping either belligerent), prevention (stopping belligerents from using its territory) and acquiescence (tolerating lawful belligerent acts such as visit and search of its merchant ships).

Each of the three duties is part of neutrality, so the complete answer covers all of them.