Loading JSON from external AJAX call into DataTable

I am using DataTables 1.9.4 with jQuery 1.8.1.

I have created a table which has zero records on page load. On click of a button I am fetching data in the form of JSON using an external AJAX call. I need to load this JSON into the already existing data table.

I read through the examples and older discussions which suggests the usage of "sAjaxSource" option and "fnReloadAjax" function to load the data into data table. To my understanding it works only if make use of DataTable's built in AJAX feature.

How to load the externally fetched JSON into an existing data table.

Thanks!