Ukraine army presses on rebel stronghold

DONETSK, Ukraine - Fighting in eastern Ukraine reached the main rebel stronghold of Donetsk on Tuesday as separatists and government troops exchanged rocket fire in neighborhoods on the edge of the city.

In a western district of Donetsk, rockets apparently fired from a government position landed in the courtyard of a one-story house, killing an elderly resident.

The spread of fighting into the city itself marks a decisive turn for the conflict, but one that will arouse fears of an alarming escalation in the humanitarian crisis gripping the country's easternmost regions.

As government troops try to tighten their encirclement of rebel citadels, officials in Kiev have warned of a spike in Russian troop numbers along the border, arousing renewed fears of intervention by Moscow.

In the morning, an Associated Press journalist saw a tank bearing the Ukrainian blue-and-yellow flag at a key checkpoint in the western suburb of Marinka, which lies on a road into Donetsk.

Rebel combatants could still be seen hunkered down in sniper positions in a nearby area closer to the center.

Defense officials played down the presence of government troops in Marinka, insisting that more fighting lay ahead before the area could be properly secured.

By the afternoon, however, there were signs the army was looking to advance farther into the city.

The shell that landed by the house in western Donetsk's Petrovsky district killed a resident whom neighbors identified only as Galina, along with her dog.

The onslaught against separatist fighters has focused recently on besieging the main rebel strongholds of Donetsk and Luhansk, as well as the smaller but strategically important town of Horlivka.

The wild card is whether Russia, which has been building up troops along the nearby border, will come to the rebels' rescue. President Vladimir Putin has faced increasing pressure from Russian nationalists urging him to send in the army to back the insurgency.

After not seeing much fighting other than a rebel attempt in May to seize the city airport, Donetsk has come under shelling in recent weeks. City authorities estimate that around 200,000 people in the city of one million have left their homes. The airport is closed, but buses and trains are still running.

Pro-Russian separatists in eastern Ukraine have been battling the Kiev government since April. Ukraine and Western countries have accused Moscow of fueling the mutiny with weapons and soldiers, a claim the Russian government has repeatedly denied.

The West has also accused Russia of most likely providing the insurgents with surface-to-air missiles that may have been used to shoot down a Malaysia Airlines jetliner over rebel-held territory on July 17, killing all 298 people on board.