The United States plans to send 1,400 additional combat Marines to Afghanistan to try to hold on to recent but fragile security gains, only months before a planned U.S. drawdown, The Wall Street Journal reported Thursday. Violence is at its worst in Afghanistan with record casualties on all sides of the conflict and with the insurgency spreading out of traditional strongholds in the south and east into once-peaceful areas in the north and west. A review by President Barack Obama last month found U.S. and NATO forces were making headway against the Taliban and al Qaeda but serious challenges remained. It said the Taliban's momentum had been arrested in much of Afghanistan and reversed in some areas. The review also said the United States was on track to begin a gradual withdrawal of its troops -- now numbering about 100,000 in a total foreign force of 150,000 -- from July 2011. "The Marine battalion could start arriving on the ground as early as mid-January. The forces would mostly be deployed in the south, around Kandahar, where the U.S. has concentrated troops over the past several months," The Wall Street Journal said, citing unnamed officials. NATO and U.S. officials in Kabul were not immediately available for comment on the report.