What is the relationship between 'Kofi Annan' and 'United Nations' in the context of the input sentence.
Options: manufacturer, legal form, operator, employer

"The United Nations engaged – there were initiatives such as the Global Compact, which Kofi Annan first telegraphed in 1999 – which have their heritage in Shell's experience in Nigeria and were a response to what was then a significant anti-globalisation movement
employer