The aggressor is the country that starts the war. But the United Nations definition which is quoted below defines the aggressor more narrowly, as the country that first uses armed force.

This definition emphasises the link between institutional ... new resolution requesting the Secretary-General to appoint a United Nations Special Envoy to Combat Islamophobia.

The UN does not endorse any definition on antisemitism' “Nonetheless, the United Nations Secretariat does not endorse any definition on antisemitism,” the plan stated. Sacha Roytman ...