WASHINGTON - The White House acknowledged on Tuesday that the 60 Syrian rebel fighters the Pentagon is training to battle Islamic State was "not enough" but said rebels were being carefully screened before being admitted into the program."It is fair to say that the United States and our coalition partners are being judicious about deciding which individuals to send into the program," said White House spokesman Josh Earnest. "Clearly, that number is not enough."The program launched in May in Jordan and Turkey was designed to train as many as 5,400 fighters a year. Defense Secretary Ash Carter said on Tuesday the Pentagon had only trained 60 so far.