U.S and allied forces in Afghanistan are preparing for stepped-up attacks after Taliban insurgents this week declared the start of their annual spring fighting season.
Their message came in an audio message that announced the start of a monumental spring operation, one aimed at defeating those it described as "western invaders," a reference to U.S.-led allied forces that are in the process of drawing down.
U.S. Defense Secretary Chuck Hagel, on a visit to Afghanistan in March, noted there are challenges ahead as U.S. forces hand over security responsibility to the Afghans.
"That transition has to be done right, it has to be done in partnership with the Afghans, with our allies," said Hagel.
For the first time, Afghan forces are in the lead this fighting season, with allied forces as backup. That means they are the prime targets for insurgents, who stepped up their attacks dramatically during the winter.
A report from the respected independent group, the Afghanistan NGO Safety Office
, says the number of insurgent attacks has grown by 47 percent in the past year. Seventy-four percent of those attacks were on Afghan national security forces and only four percent against international troops.
Jonah Blank, an analyst with the Rand Corporation, said Taliban fighters have calculated that going after allied forces isn't as effective as targeting Afghan troops.
“The Taliban [is] trying to assert its dominion or its power over the national security forces and to put some fear into them," he said. "They don't take on ISAF or U.S. troops as much because they get killed when they do that. There isn't any percentage in it for them now that we have made clear that we will be withdrawing and we will be leaving only a fairly small force when we leave."
The United States is due to pull out most of the 66,000 troops it has in Afghanistan by December 2014, and is still deciding how many it will leave behind.
How Afghan forces do this fighting season may help answer that question.