If one nation violates international law, it is up to other nations to use tactics or actions such as severance of diplomatic relations or, as a last resort___

Persuasive; Coercive; Boycotts; War.

Explanation:

If one nation violates international law, it is up to other nations to use persuasive tactics or coercive actions such as severance of diplomatic relations, boycotts or, as a last resort war.

The global standard for acting on a country which has erred or violated an international law, is to first use a persuasive tactics as a means of peaceful resolution but if the country isn't cooperating or yielding, then it is allowed to you a coercive approach such as boycotting its interests or declaring a war.

a is the final ! : )