WASHINGTON — Dusty and remote, the Syrian city of Kobani has become an unlikely spoil in the war against Islamic State militants — and far more of a strategic prize than the United States wants to admit.

Perched on Turkey’s border, the city of about 60,000 has been besieged for weeks by IS fighters. Kobani is now a ghost town: the U.N. estimates fewer than 700 of its residents remain as its people flee to safety in Turkey.

The Obama administration has declared Kobani a humanitarian disaster, but not a factor in the overall strategy to defeat the Islamic State group.

“Kobani does not define the strategy of the coalition with respect to Daesh,” Secretary of State John Kerry told reporters in Cairo earlier this week, using an Arabic acronym for the Islamic State group. “Kobani is one community, and it’s a tragedy what is happening there, and we don’t diminish that.”

But, Kerry said, the primary U.S. military focus is in neighboring Iraq.

But this week, the U.S. dramatically upped its air power strikes against IS in and around Kobani, including 53 strikes over the last three days alone. Several hundred IS fighters were killed, the Pentagon said.

Now, the U.S. cannot afford to lose Kobani, said Robert Ford, the former U.S. ambassador to Syria. That means the city’s fate is tied, in part at least, to the success of the U.S.-led strategy against the Islamic State.

“The most important thing about Kobani now is that if it falls to the Islamic State, it would be seen as a defeat for the Americans, and thus would touch on the credibility of the American policy to contain and degrade the Islamic State,” said Ford, now at the Middle East Institute in Washington.

“We have made a real effort to help the defenders in Kobani by targeting various Islamic State assets,” he said.

“And if it falls nonetheless, then it makes it looks like the U.S. military couldn’t contain that, and that’s how it would be seen in the region.”

Said Navy Rear Adm. John Kirby, the Pentagon’s spokesman on Thursday: “We never said Kobani didn’t matter.”