A lesson in why air power alone won't be enough to "degrade and destroy" ISIS military forces.

A Kurdish city on the border with Turkey has been under siege for more than a week now, despite at least 2 American led attacks from the air on ISIS positions. The Kurds are reporting that the terrorists have captured a small town near the border city of Kobani and that tanks and other armored vehicles are trying to surround the city.

Reuters:

More than a month since the U.S. military began striking Islamic State targets in Iraq, and four days since it extended the campaign into Syria, there are signs fighters are lowering their profile in areas they control to become a harder target.

General Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, said this week's strikes in Syria had disrupted Islamic State's command, control and logistics capabilities.

But Dempsey said a Western-backed opposition force of 12,000 to 15,000 would be needed to retake areas of eastern Syria controlled by the militants. U.S. assessment teams have arrived in Saudi Arabia to map out a program expected to train more than 5,000 opposition fighters in the first year.

"We have to do it right, not fast," Dempsey said.

The air campaign has yet to halt Islamic State's advance in Syria, where fighters have laid siege to a Kurdish town on the Turkish border, sending 140,000 refugees across the frontier since last week in the fastest exodus of the three-and-a-half-year-old civil war.

The main battle in northern Syria has been visible from across the border in Turkey. The boom of artillery and bursts of machine-gun fire echoed across the area and at least two shells hit a vineyard on the Turkish side of the border, though there were no immediate reports of casualties inside Turkey.

"We're afraid. We're taking the car and leaving today," said vineyard owner Huseyin Turkmen, 60, as small arms fire rang out in the Syrian hills just to the south.

Islamic State fighters appeared to have taken control of a hill 10 km (6 miles) west of Kobani from where the YPG, the main Kurdish armed group in northern Syria, had been attacking them.

The British-based Syrian Observatory for Human Rights, which monitors the war, said Islamic State fighters had also taken control of a village around 7 km (4 miles) east of Kobani.

Kurdish forces said on Thursday they had pushed back the advance on Kobani, also known as Ayn al-Arab, but appealed for U.S.-led air strikes on the insurgents' tanks and heavy weapons.

Note that General Dempsey is describing a force of "10-15,000" that doesn't exist. We're setting up in Saud Arabia to train 5,000 rebels with no guarantee they share our primary goal of destroying ISIS. Their main concern is defeating President Assad's forces. Can we really expect another 10,000 rebels to assist us in our war against ISIS?

Questions should also be raised about the efficiency and value of the strikes.

The U.S. military said its planes blew up four Islamic State tanks in eastern Syria and hit a number of targets in Iraq.

The Syrian Observatory monitoring group said one U.S.-led strike in eastern Syria had killed an "important" Islamic State figure on a motorbike. It did not identify the victim.

Assad's Syrian government has not objected to the U.S.-led campaign against some of his most powerful foes. Washington says it wants to defeat Islamic State without helping Assad remain in power and hopes other anti-Assad groups can fill the vacuum.

But while U.S. planes have been striking Islamic State in eastern Syria, Assad's air force has been bombing other rebel groups in the west of the country, and his troops and allied Lebanese Shi'ite militia have advanced.

Syrian warplanes dropped projectiles including "barrel bombs" - oil drums filled with explosives - in Hama, Idlib, Homs and Aleppo provinces and around Damascus, the Observatory said.

How many multi million dollar smart bombs or missiles did we use to blow up 4 tanks? That's been the story of our bombing campaign. We blow up a tank here, a vehicle there, or take out a checkpoint. Of course, it's hard when the enemy doesn't mass it's troops and equipment. And ISIS appears to be changing tactics so that they are less visible than before.

But the inefficiency of the air campaign points to the necessity for western/American ground troops to defeat the terrorists. That's what it will come to in the end, and the generals and the president know it.