Ukraine's last cease-fire collapsed quickly. This one may last — because it's in Russian President Vladimir Putin's interests.

Putin's goal of keeping Ukraine in Russia's orbit remains the same. But recent battlefield gains by pro-Russia rebels mean that Moscow has the upper hand in peace talks that will help determine Ukraine's future.

From the onset of the Ukrainian crisis, Putin's objective has been to secure enough autonomy for Ukraine's Russian-speaking east that the region can keep its close ties to Russia — and to prevent Ukraine from ever joining NATO.

In March, after Ukraine ousted its pro-Russian president, Moscow annexed the Ukrainian peninsula of Crimea. But while many in Ukraine and the West fear Putin wants to seize more land, that doesn't seem to be his preferred option. If he wanted to grab more land in Ukraine, he could have easily done so.

Putin apparently has calculated that the price would be too high, both because of the devastating economic punishment the West would impose and because of the need to spend tens of billions of dollars to support eastern Ukraine. With the Russian economy in recession, that's a liability the Kremlin can't afford.

Putin has opted for a more devious course.

He may have hoped that the pro-Russian mutiny that broke out in the Donetsk and Luhansk regions in April would force Kiev to make compromises and offer the rebel regions broader powers. If so, that was a miscalculation.

Kiev didn't compromise, and the West slapped several waves of sanctions on Moscow, brushing aside the Kremlin's denials that it was fomenting the rebellion with soldiers and weapons. Meanwhile, Ukraine's military operation against the rebels, hesitant at first, steadily gained momentum and by late August had driven the rebels into a corner.

Putin couldn't afford to see the insurgents defeated, and the rebel counter-offensive sharply turned the tide, raising the prospect of Ukraine losing more territory and making Kiev more interested in negotiations.

Ukraine and the West accused Russia of sending thousands of regular troops into Ukraine to spearhead the rebel onslaught. Putin reportedly countered in a phone conversation with European Commission chief Jose Manuel Barroso, saying if he had wanted an invasion, he could have taken the Ukrainian capital in two weeks.

He probably could have.

Ukrainian troops — weakened by two decades of insufficient funding and rampant graft and demoralized by the string of rebel gains — would be unlikely to mount a serious resistance in the face of a full-fledged invasion by the Russian army, which has undergone an extensive weapons modernization program and conducted large-scale maneuvers to enhance troops' coordination.

The United States and other NATO members have made it clear they wouldn't engage Russia militarily, and any weapons they might offer would take months of training for Ukrainian troops, rendering them irrelevant. That leaves sanctions as the only tool available to stem a Russian onslaught.

But by brokering a cease-fire, Putin has made it clear that he doesn't want to go down that road — for now.

The one-page, 12-point cease-fire deal looks vague and fragile. It doesn't specify the current front lines, and doesn't say what status the rebel provinces may get.

While Putin and Ukrainian President Petro Poroshenko may have reached a preliminary understanding on what a political compromise could look like, putting it on paper will be extremely challenging, particularly in the run-up to Ukraine's parliamentary elections in October.

The Kremlin can count on two things — the insurgency, and Ukraine's hobbled economy — to make Kiev reckon with Moscow's demands. Putin appears to be betting that it will

If it doesn't, he has made clear that the military option will remain on the table.

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Isachenkov has covered Russia and other ex-Soviet nations for the AP since 1992.