SYRIA -- The thick fog meant the drive to the front line inside Syria was slow.

We were about 40 miles from Raqqa, the headquarters of ISIS, but their fighters were just a few miles away, and no one wanted to make a wrong turn.

Past deserted villages, we finally reached the last line of defense.

It wasn't much. One of the soldiers looked like he was barely into his teens. These are the Syrian rebels the U.S. is training and equipping.

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Until a few months ago, the whole area was controlled by ISIS.

Gloomy days are a nightmare for rebel forces guarding the front lines. ISIS militants use the fog as cover to launch sneak attacks. The rebels can't see them coming until it's too late to stop them.

The group leader told us warplanes can't see them either. While he said he was grateful for American support, he hadn't actually seen any of the U.S. Special Forces now on the ground.

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But Commander Lewland Rojava had. We met him at his base camp deep inside Syria.

He told us they are mainly discussing coordination on the ground, weapons and ammunition, and who gets them. They also want to see how successful we are in fighting ISIS on the ground.

We also asked villagers what they thought of U.S. troops inside Syria.

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One said if they bring peace and stability, they are welcome. Another said he was happy when he heard the Americans were coming.

The commander said once U.S. forces see for themselves what they're up against, they'll realize they need armored vehicles and heavy weapons in addition to guns and ammunition. He also said depending on how it goes, maybe America will send more forces.