LONDON — The Pentagon on Friday announced it was ending its failed $500 million program to "train and equip" Syrian rebels and replacing it with a far less ambitious plan, defense officials said.

The "training" part of the program — which managed to field only "four or five" Syrian rebels into the battle against ISIS at a $50 million price tag — has been halted, according to senior defense officials.

Instead of combat training for the rebels, they will now be used as "enablers" to identify ISIS targets on the ground for U.S. and coalition airstrikes. They will also be advised on how to interact with U.S. military "at a distance," and there will be no American forces on the ground in Syria

The "equip" part of the program, which provided small arms, ammunition and vehicles, will be dramatically reduced to providing weapons to some 5,000 friendly moderate Syrian rebels to carry on the fight against both ISIS and presumably, the regime of Syrian President Bashar Assad.

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The remaining $450 million will be spent on this scaled back plan.

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In a statement, Defense Secretary Ash Carter confirmed the immediate move, and said he believes the revamped initiative will help "increase the combat power" of the anti-ISIS fighters in Syria and stop them from advancing.

But many of the weapons and vehicles provided to the first group of Syrian rebels had quickly fallen into the hands of enemy forces, such as the al Qaeda-backed Al Nusra Front.

The initial "train and assist" program aimed at aiding and equipping 54,000 moderate rebels by the end of this year. As of now, that number is somewhere around 100, and only a handful of them have actually been engaged in any combat operations against enemy forces.

Pentagon spokesman Peter Cook said coalition forces have relied on other efforts to crush the Islamist militants, including supporting the counter-ISIS fighters in Kobani in northern Syria, where they recaptured a key border crossing and held off ISIS.

Carter, speaking to reporters in London on Friday, said the U.S. "remains committed" to the idea of training rebel forces but said officials "have been looking now for several weeks at ways to improve" the current program.

"I wasn’t satisfied with the efforts on that regard, so we are looking at different ways to achieve basically to the same kind of strategic objective," he said. "We have devised a number of different approaches to that moving forward, and President Obama ... I think we will be hearing very shortly from him in that regard."