KABUL (Reuters) -- The majority of the 17,000 extra U.S. troops being sent to fight a growing Taliban-led insurgency in southern and western Afghanistan should be on the ground by mid-July, the U.S. military has said.
A further 4,000 troops are arriving to train Afghan security forces and they will be deployed by August.
Washington pledged to send 21,000 additional troops to Afghanistan to reinforce security ahead of presidential elections scheduled for Aug. 20 and to support NATO-led troops that have struggled to fight an escalating insurgency there.
"10,000 Marines are beginning to arrive now and will continue to arrive for the next month and a half or so and they will be principally located in Helmand but also in Farah," said Colonel Greg Julian, spokesman for U.S. forces.
Helmand Province in southern Afghanistan and Farah in the west are among the areas that have seen the fiercest fighting as insurgents gathered strength in recent years, despite the presence of a growing number of foreign troops.
"Everyday we are faced with suicide bombers, an increased number of improvised explosive devices," Defense Ministry spokesman General Zahir Azimi said.
"If the violence wasn't increasing there would be no need for the presence of foreign forces and Afghan forces themselves could handle this issue."
Some 7,000 U.S. Army troops are also being deployed to southern Kandahar Province.
"3,500 are already on the ground in Kandahar with additional helicopters. Following that an additional 3,500 army troops will arrive in Kandahar and will be located in rural areas of that province," Julian told a news conference.
All 21,000 troops will be deployed by August, another U.S. military spokesman said, but declined to comment further.
The 4,000 training troops will be sent mainly to southern and western Afghanistan and more than half will train and mentor Afghan police, who are a younger force than the Afghan National Army (ANA) and have suffered from poor training, illiteracy, and corruption.
The ANA has also expanded its forces to 90,0000 troops from about 83,000, and will boost numbers further for the August poll, Azimi said.
"Currently we have 90,000 ANA forces and we expect to increase this number during the elections to 95,000 forces as well as the additional forces of the Afghan National Police and the international forces," he told journalists.
The Afghan army, described by U.S. military officials as a success story, now leads more than twice as many military operations per week in Afghanistan, compared with this time last year, a spokesman for NATO-led forces said.