The three-week-long Islamic State siege of the Syrian town of Kobani is rapidly intensifying. On Monday, fighters were said to have raised the black ISIS flag over at least one building in the eastern part of the city as vicious street-to-street battles unfolded. Reporting from southern Turkey, journalist Harald Doornbas noted that a second flag had gone up just southeast of the city.

The good news is the Syrian Kurds have (so far) kept ISIS from breaching the center of the city. The bad news is everything else. Kobani, also known as Ayn al-Arab, is just six miles from the Turkish border, over which more than 100,000 civilians fled when the Islamic State attack began in late September.

The advance of the Islamic State fighters into a strategically important Syrian city is a development that U.S.-led airstrikes were supposed to preclude. But as many are suggesting, the coalition efforts to stem the Islamic State onslaught have been ineffective. This is, at least in part, because ISIS has changed its tactics.

"In Syria and Iraq, they took down many of their trademark black flags, and camouflaged armed pickup trucks," The Wall Street Journal wrote of ISIS. "They also took cover among civilians." The group is also said to have decentralized some of its command structure, adjusted its movements to nighttime, and eschewed the frequent use of cellphone and radio communications.

In some ways, ISIS has come to resemble the group from which it splintered, al-Qaeda, which worked more covertly. The Journal adds that the group is said to have "also eased up on enforcement of their strict interpretation of Islamic law."

"We expected that they would adapt and change their behavior and tactics once airstrikes begun," Rear Admiral John Kirby told reporters at the Pentagon on Friday, hardly concealing his frustration with the collective mood of impatience.

While Kirby touted successes that included the targeting of oil refineries and other ISIS financial and communication operations, his comments come against the backdrop of a growing skepticism about the campaign. Late last month, the Syrian Observatory for Human Rights drew attention to accounts of civilian casualties caused by the airstrikes. This report dovetailed with word of a popular backlash against the American efforts in Syria, where they are perceived as not only aiding Syrian dictator Bashar Assad, but also harming support for the moderate rebel groups fighting there.

In the meantime, not only are Islamic State forces still holding territory, they continue to advance.

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