U.S. Secretary of State John Kerry has hailed a day of "productive" talks with new Afghan leaders at the presidential retreat of Camp David, in Maryland.
Kerry told a news conference that the meetings on March 23 "underscore the enduring nature of the friendship."
His remarks came after day-long talks with Defense Secretary Ashton Carter, Afghan President Ashraf Ghani, and Chief Executive Officer Abdullah Abdullah.
Carter said Washington maintains an "unwavering commitment to a strong and strategic partnership with Afghanistan."
He added that the administration would be asking Congress to fund the Afghan security troop levels at "an end strength level of" 352,000 to at least 2017.
Carter said the "Afghan and coalition military commanders have jointly recommended this force size… to ensure that the security gains we've made together are lasting."
Kerry said that in a separate initiative, Washington will commit up to $800 million to a new development partnership to promote sustainable and transparent economic reform.
Ghani has requested a slowdown of the U.S. military withdrawal from Afghanistan.
The NATO combat mission formally ended in December, but the United States has 9,800 troops in Afghanistan.
That number is planned to be cut back to 5,500 in 2016.
Ghani said any decision about future U.S. troop levels would be made by President Barack Obama.
Ghani said "the security environment is difficult” but “our armed forces, an all-volunteer force, are ready to do their patriotic duty."
Kerry said Obama was "actively considering" Ghani's request for flexibility.
Ghani is expected to discuss U.S. troop levels with Obama at the White House on March 24.
Ghani's relationship with Washington stands in stark contrast to that of his predecessor, former President Hamid Karzai, whose antagonism towards the United States culminated in a refusal to sign a key security agreement before leaving office last year.
Ghani signed the Bilateral Security Agreement within days of becoming president in September, and he has since enjoyed a close relationship with Washington.