WASHINGTON (Reuters) - Even as thousands of additional American troops head to Afghanistan, a U.S. government watchdog is warning that tens of billions of dollars could be wasted unless changes are made in the training of Afghan security forces.

Commandant of the Marine Corps Gen. Robert B. Neller speaks with Marines with Task Force Southwest at Bost Airfield, Afghanistan, June 20, 2017. Courtesy Justin T. Updegraff/U.S. Marine Corps/Handout via REUTERS

Deficiencies in the Afghan forces, including the military and police, are getting renewed attention after U.S. President Donald Trump’s administration decided to send more than 3,000 additional troops to the country where the United States has been engaged in its longest war.

Washington has spent $70 billion training Afghan forces since 2002, and is still spending more than $4 billion a year, according to a report from the Special Inspector General for Afghanistan Reconstruction, or SIGAR, published on Thursday.

Despite those sums, Afghan security forces are struggling to prevent advances by Taliban insurgents more than 16 years after the United States invaded Afghanistan to topple the Islamist Taliban government that gave al Qaeda the sanctuary where it plotted the Sept. 11, 2001, attacks.

According to U.S. estimates, government forces control less than 60 percent of Afghanistan, with almost half the country either contested or under the control of insurgents.

The report said U.S. forces focused on carrying out military operations during the initial years after the 2001 invasion, rather than developing the Afghan army and police.

When the United States and NATO did look to develop the security forces, they did so with little input from senior Afghan officials, according to the report.

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At one point, the report said, training for Afghan police officials used Power Point slides from U.S. and NATO operations in the Balkans.

“The presentations were not only of questionable relevance to the Afghan setting, but also overlooked the high levels of illiteracy among the police,” the report said.

John Sopko, the head of SIGAR, said that one U.S. officer watched TV shows such as “Cops” and “NCIS” to understand what to teach Afghan officials.

Sopko said the U.S. government approach to Afghanistan lacked a “whole of government approach” in which different agencies such as the State Department and Pentagon coordinate efforts. The inability of embassy officials in Kabul to venture far outside their secure compound also affected oversight and coordination, he said.

‘VERY REAL IMPROVEMENTS’

The goal of U.S. policy remains enabling local forces to defeat the Taliban and secure the country so economic development can proceed.

“Victory would look like people in the Government of Afghanistan (being able to) handle this threat from the terrorists, using their own security forces, with international mentors probably there for many years to come,” U.S. Defense Secretary Jim Mattis said recently.

Michael Kugelman, a South Asia specialist at the Woodrow Wilson Center, a Washington think tank, said that while the Afghan forces had major shortcomings, including their ability to collect intelligence and hold territory, their progress should not be overlooked.

“It is easy to forget the progress that the security forces have made amid all the doomsday rhetoric, but there have been very real improvements in the Afghan security forces. For instance, the special forces have become jewel of the Afghan security forces,” Kugelman said.

Afghan President Ashraf Ghani said on Wednesday the country’s army was not only better trained and profiting from a new generation of soldiers but had gained experience after huge cuts in the U.S.-led international force under former U.S. President Barack Obama forced Afghans to assume a bigger role in the fighting.