WASHINGTON (AP) - Defense Secretary Jim Mattis is defending the use of active duty troops on the U.S.-Mexican border, saying that in some ways it provides good training for war.

  

Mattis spoke on his way to visit U.S. troops along the border in south Texas.

  

The Pentagon chief said that within a week to 10 days the 5,800 troops currently deployed for the border mission will have accomplished all the tasks requested by Customs and Border Protection. He added that additional tasks are likely to be added, and he did not say how soon the whole mission might end.

  

Mattis declined to offer an estimate of the mission's cost, saying the internally reported numbers he has seen thus far are not accurate.