Canadian Forces: Direct Action 4.1 is a heavy mod for SWAT 4. It's developed by the Canadian Army as a free training tool for military and police organizations.
"After about a year of development, the training tool, based on SWAT 4, to be used by soldiers and police to train and visualize operations in complex urban environments has been released to the public! Developed in conjunction with the Training Innovation Division of the Federal Law Enforcement Training Center; CF:DA is a tool provided to military, police and security agencies free of charge to assist in your training requirements." Source: Blue's News