US President Barack Obama says the US will deploy an additional 250 military personnel to Syria, including special forces troops, to train and assist local forces fighting Islamic State militants.

"Just as I have approved additional support for Iraqi forces against ISIL [alternative name for Islamic State], I decided to increase U.S. support for local forces fighting ISIL in Syria. A small number of American special operations forces are already on the ground in Syria and their expertise has been critical as local forces have driven ISIL out of key areas. So given this success, I have approved the deployment of up to 250 additional U.S. personnel in Syria, including special forces to keep up this momentum," Obama said.