Write SQL query to solve given problem: What are the names of the three nations where the longest river that empties into the Atlantic Ocean stretches to?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT DISTINCT T1.Country FROM city AS T1 INNER JOIN located AS T2 ON T1.Name = T2.City INNER JOIN river AS T3 ON T3.Name = T2.River WHERE T3.Name = ( SELECT Name FROM river WHERE Sea = 'Atlantic Ocean' ORDER BY Length DESC LIMIT 1 )