NSC spokeswoman Caitlin Hayden explained that the request is part of the administration's broader Counterterrorism Partnerships Fund.
"These funds would help defend the Syrian people, stabilize areas under opposition control, facilitate the provision of essential services, counter terrorist threats, and promote conditions for a negotiated settlement."
While the White House acknowledged it sees "no military solution to [the Syrian] crisis," the proposed funding would provide military assistance to "appropriately vetted elements of the moderate Syrian armed opposition" in order to help "the Syrian people defend themselves against regime attacks" and terrorists.
Syrian opposition President Ahmad al-Jarba, during his meetings with U.S. officials in Washington in May, planned to "ask for more weapons, specifically an airforce to fight barrel bombs and scud missiles," an opposition representative told UPI in May.
Speaking at the U.S. Institute of Peace in Washington during his May visit, Jarba underlined the opposition's need for lethal aid to counter the regime's attacks:
"We have a problem with air raids, forces and barrel bombs. We want weapons to neutralize the air force.
"... We need effective and efficient weapons. We commit to keep them in the right hands. We want a political solution."
Hayden said Thursday that the $500 million to equip and train armed Syrian opposition members "would build on the administration's longstanding efforts to empower the moderate Syrian opposition, both civilian and armed, and will enable the Department of Defense to increase our support to vetted elements of the armed opposition."