An Afghan security personnel keeps watch as a helicopter flies during the Afghanistan Air Force readiness performance program at a military airfield in Kabul, Afghanistan February 11, 2016. REUTERS/Ahmad Masood

WASHINGTON (Reuters) - The United States plans to provide more than $3 billion a year in support for the Afghan national security forces from 2018 through 2020, U.S. Special Representative for Afghanistan and Pakistan Richard Olson said on Tuesday.

Speaking at a think tank, Olson also said the United States planned to ask Congress for about $1 billion a year in development and economic assistance for Afghanistan from 2018 through 2020.