Tensions grow in Ukraine over Russia troop buildup

Local residents inspect the damage after night shelling on a local market in Donetsk, eastern Ukraine, Wednesday. Air strikes and artillery fire between pro-Russian separatists and Ukrainian troops in the eastern city of Donetsk have brought the violence closer than ever to the city center, as Kiev's forces move in on the rebel stronghold.
Local residents inspect the damage after night shelling on a local market in Donetsk, eastern Ukraine, Wednesday. Air strikes and artillery fire between pro-Russian separatists and Ukrainian troops in the eastern city of Donetsk have brought the violence closer than ever to the city center, as Kiev's forces move in on the rebel stronghold.

DONETSK, Ukraine (AP) - The steadily advancing Ukrainian army is setting its sights on the largest rebel-held city in eastern Ukraine, while Western officials on Wednesday warned that a Russian military buildup on Ukraine's border could herald a major incursion to protect the separatists.

President Vladimir Putin has resisted mounting pressure from Russian nationalists to send the army in to back the mutiny in eastern Ukraine. Even though the U.S. and NATO would be unlikely to respond militarily, the West would be certain to impose major sanctions that would put the shaky Russian economy on its knees - and could quickly erode Putin's power.

Russia already is showing signs of economic dismay from sanctions imposed earlier this year, but Putin on Wednesday showed Moscow aims to fight back, calling on government agencies to develop a list of agricultural imports from sanctions-imposing countries that could be banned for up to a year.

The state news agency RIA Novosti later quoted an official from Russia's plant and veterinary oversight service as saying all U.S. agricultural products would fall under the ban.

Pro-Russian separatists in eastern Ukraine have been fighting the Kiev government since April. Ukraine and Western countries have accused Moscow of backing 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 passenger jet over rebel-held territory on July 17, killing all 298 people on board. The prime minister of The Netherlands, whose nationals made up more than half of the victims, said Wednesday that the search for victims' remains is being halted because fighting in the area of the crash site makes it too dangerous to continue.

Polish Prime Minister Donald Tusk said he believed "the threat of a direct intervention (by Russia) is definitely greater than it was a few days ago, or two weeks ago."

A U.S. official told the Associated Press that U.S. intelligence shows Russian forces continue to shell Ukrainian positions from inside Russian territory and send heavy weaponry - including artillery, armored vehicles and air defense equipment - from a separatist training facility in southwest Russia. The official was speaking on condition of anonymity because he wasn't authorized to discuss intelligence matters publicly.

Adding to the concern is Russia's proposal in recent days for a humanitarian mission to eastern Ukraine.

"We share the concern that Russia could use the pretext of a humanitarian or peacekeeping mission to send troops into eastern Ukraine," NATO spokeswoman Oana Lungescu said in an e-mailed statement.

The Ukrainian Foreign Ministry said NATO Secretary-General Anders Fogh Rasmussen will visit Kiev on Thursday to meet President Petro Poroshenko and other officials.

Humanitarian concerns are rising as Ukrainian forces come closer to encircling the city of Donetsk and continue their fight against the pro-Russia rebels in the large city of Luhansk.

Moscow has pushed for a cease-fire in the east, but the Ukrainian government has appeared bent on riding the momentum of a series of recent military advances to crush the rebels.

While an overt military move into Ukraine would be deeply risky for Russia, Putin also faces agitation from nationalists who want Russia to take more assertive action.