December 2001 saw the creation of the NATO-led International Security Assistance Force  to assist the Afghan Transitional Administration and the first post-Taliban elected government. With a renewed Taliban insurgency, it was announced in 2006 that ISAF would replace the U.S. troops in the province as part of Operation Enduring Freedom. The British 16th Air Assault Brigade  formed the core of the force in southern Afghanistan, along with troops and helicopters from Australia, Canada and the Netherlands. The initial force consisted of roughly 3,300 British, 2,000 Canadian, 1,400 from the Netherlands and 240 from Australia, along with special forces from Denmark and Estonia and small contingents from other nations. The monthly supply of cargo containers through Pakistani route to ISAF in Afghanistan is over 4,000 costing around 12 billion in Pakistani Rupees.
Question: How many countries had forces in Afganistan, replacing the US troops?
Answer: 4