David Jackson and Jim Michaels

USA TODAY

President Obama asked Congress Thursday for $500 million to train and arm members of opposition forces in Syria, part of an effort to stem insurgent violence that has spilled over into neighboring Iraq.

The proposed assistance can "help defend the Syrian people, stabilize areas under opposition control and facilitate the provision of essential services, counter terrorist threats, and promote conditions for a negotiated settlement," the administration said in its budget request to Congress.

Potential recipients of the money — opponents of the Syrian government headed by Bashar al-Assad — will be vetted, officials said. Lawmakers have expressed concern that weapons and money sent to Syrian rebels might wind up with enemies of the United States.

"This funding request 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," said Caitlin Hayden, a spokesperson for the National Security Council.

The administration's budget request includes $1.5 billion for a "Regional Stabilization Initiative" that involves the Syrian opposition as well as neighboring countries Jordan, Lebanon, Turkey and Iraq.

Details of the assistance have not been determined by the Pentagon, but it will involve training outside Syria, possibly Jordan, said a senior defense official who spoke on condition of anonymity because the details were not authorized to be released publicly.

The military could train a small cadre of fighters who would then return to Syria to share their knowledge or it could mean training entire units of rebels, the official said.

Defense Secretary Chuck Hagel "has directed his staff to begin developing more detailed plans to carry out the train-and-equip mission, if approved by Congress," Rear Adm. John Kerry, the Pentagon press secretary, said in a statement.

The initiative would be part of the "Counter-Terrorism Partnerships Fund" that Obama proposed during a foreign policy address last month at the U.S. Military Academy at West Point, N.Y.

Hayden said the United States continues to believe that "there is no military solution to this crisis," and the United States "should not put American troops into combat in Syria."

Jeff White of the Washington Institute for Near East Policy, and former Defense Intelligence Agency official, said the $500 million proposal is "a pretty good chunk of change," and "would buy some substantial assistance."

The United States has already been operating covert programs to supply rebels with weapons, and is providing non-lethal aid to opposition groups, White pointed out. The rebels have also been supplied with U.S. TOW anti-tank missiles, though it is not clear if they are coming from the United States or another country.

Those programs have allowed the administration to establish links with moderate groups, he said, and "sort of the set the groundwork for a larger lethal aid program."

The United States is also looking to assist resistance to the Sunni extremist group known as the Islamic State of Iraq and the Levant (ISIL), which has taken land on both sides of the Syria-Iraq border.

Hayden said the assistance request "marks another step toward helping the Syrian people defend themselves against regime attacks, push back against the growing number of extremists like ISIL who find safe-haven in the chaos, and take their future into their own hands by enhancing security and stability at local levels."

The Syria proposals are part of an overall $65.8 billion budget request for overseas contingency operations that include a variety of Pentagon and State Department programs.

The overall budget plan includes a previously announced $1 billion in defense assistance to Central and Eastern European nations, a response to Russian annexation of land from Ukraine.

The total $65.8 billion overseas package is about $21 billion less than first projected, officials said, reflecting U.S. plans to withdraw U.S. combat troops from Afghanistan.

The counter-terrorism fund also includes money for stabilizing Syria's neighbors, including Iraq, where Sunni extremists have seized towns and battled Iraqi security forces, posing a threat to Baghdad.

On Thursday, prominent Shiite leaders called for the removal of Iraqi Prime Minister Nouri al-Maliki, the Associated Press reported, as parliament prepared to start work next week on putting together a new government. The United States has put pressure on Maliki and his government to form a more inclusive government, though they have stopped short of calling for his removal.

Signs of sectarian violence are surfacing in Baghdad where 12 people were killed in a Shiite neighborhood of the capital and police found the bodies of eight Sunnis south of the capital, the Associated Press reported.