The key Syrian border city of Kobani will soon fall to ISIS, but that's not a major U.S. concern, several senior U.S. administration officials said.
If Kobani falls, ISIS would control a complete swath of land between its self-declared capital of Raqqa, Syria, and Turkey - a stretch of more than 100 kilometers (62 miles).
The U.S. officials said the primary goals are not to save Syrian cities and towns, but to go after ISIS' senior leadership, oil refineries and other infrastructure that would curb the terror group's ability to operate - particularly in Iraq.
Saving Iraq is a more strategic goal for several reasons, the officials said. First, the United States has a relationship with the Iraqi government. By contrast, the Obama administration wants Syrian President Bashar al-Assad to step down.
Another reason: The United States has partners on the ground in Iraq, including Iraqi forces and Kurdish fighters known as Peshmerga.
But on Tuesday, a top U.N. official implored world leaders to take action as Syrian Kurdish fighters defending Kobani are dangerously outmatched.
"They have been defending themselves with great courage. But they are now very close to not being able to do so," said Staffan de Mistura, the U.N. special envoy for Syria.
"They are fighting with normal weapons, whereas the ISIS has got tanks and mortars," he said. "The international community needs to defend them. The international community cannot sustain another city falling under ISIS."
See more on this developing story on CNN.com