How is a country's foreign policy related to sovereignty

A country's foreign policy is related to sovereignty in regards to its demands of legitimacy and upholding of its own sovereignty as well as respect and dealings with other nations which have the same demands of sovereignty. Sovereignty or control of a given territory by a governmental entity is a major feature of world governance since the Treaty of Westphalia that first created nation states. A state is influenced by sovereignty relative to its foreign policy in that states engage with other sovereign states in the international space as well as they either support or contradict the norms of sovereignty. For example the United States decided to invade Iraq in 2003 which was a "sovereign" nation state, in doing so the U. S. decided to infringe upon the sovereignty of Iraq to achieve its foreign policy objectives.