By Sabrina Tavernise, Eric Schmitt and Rick Gladstone

New York Times News Service

Diplomatic aftermath — The downing of a commercial Boeing 777 in the Ukrainian war zone Thursday inflamed an already volatile international crisis and may bolster President Barack Obama’s efforts to isolate Russia if evidence points to complicity by Moscow’s separatist allies.

Obama was careful not to offer any judgments in his only public comments on the crash. But Vice President Joe Biden said bluntly that the aircraft with 298 people on board was “blown out of the sky,” and the White House late Thursday issued a statement linking the crash to a crisis “fueled by Russian support for the separatists.”

If investigators are able to confirm suspicions that the Malaysia Airlines jet was brought down by a surface-to-air missile fired by pro-Russian rebels who mistook it for a military aircraft, U.S. officials expressed hope that the tragedy will underscore their case that Moscow has been violating Ukrainian sovereignty.

While Obama had imposed new sanctions on Russia just a day before, Europeans refused to adopt similar measures out of fear of jeopardizing their own economic ties.

The Obama administration already has additional sanctions prepared that could be put into effect quickly if Obama so chooses.

“The question is does this finally move the Europeans across that threshold,” said a senior administration official, who insisted on anonymity to speak more candidly. “I don’t know, but how could it not?”

European officials were cautious in their initial reactions, seeking time and information before jumping to possible consequences, and were reluctant to assign blame. But most of the slain passengers were Europeans. The majority of them, 154 in all, were from the Netherlands, where the flight originated, which could increase pressure on European governments to respond.

The presidents of the European Council and European Commission, which are central governing bodies for the continental union, called for “an immediate and thorough investigation” to establish responsibility “as quickly as possible.”

— New York Times News Service

GRABOVO, Ukraine — A Malaysia Airlines Boeing 777 with 298 people aboard exploded, crashed and burned on a flowered wheat field Thursday in a part of eastern Ukraine controlled by pro-Russia separatists, blown out of the sky at 33,000 feet by what Ukrainian and U.S. officials described as a Russian-made anti-aircraft missile.

Ukraine accused the separatists of carrying out what it called a terrorist attack.

U.S. intelligence and military officials said the plane had been destroyed by a Russian SA-series missile, based on surveillance satellite data that showed the final trajectory and impact of the missile but not its point of origin.

There were strong indications that those responsible may have errantly downed what they had thought was a military aircraft only to discover, to their presumed shock, that they had struck a civilian airliner. Everyone aboard was killed, their corpses littered among wreckage that smoldered late into the summer night.

Russia’s president, Vladimir Putin, blamed Ukraine’s government for creating what he called the conditions for the insurgency in eastern Ukraine, where separatists have bragged about shooting down at least three Ukrainian military aircraft.

But Putin did not specifically deny that a Russian-made weapon had felled the Malaysian jetliner.

Whatever the cause, the news of the crashed plane, with a passenger manifest that spanned at least nine countries, elevated the insurgency into a new international crisis.

The day before, the U.S. had slapped new sanctions on Russia for its support of the pro-Kremlin insurgency, which has brought East-West relations to their lowest point in many years.

Another hit for Malaysia

Making the crash more of a shock, it was the second time within months that Malaysia Airlines suffered a mass-casualty flight disaster with international intrigue — and with the same model plane, a Boeing 777-200ER.

The government of Malaysia’s prime minister, Najib Razak, is still reeling from the unexplained disappearance of Flight 370 in March, somewhere over the Indian Ocean. He said he was stupefied at the news of Flight 17, which had been bound for Kuala Lumpur, the Malaysian capital, from Amsterdam with 283 passengers, including three infants, and 15 crew members.

Aviation officials said the aircraft had been traveling an approved and heavily trafficked route over eastern Ukraine, about 20 miles from the Russia border, when it vanished from radar screens at 2:15 p.m. local time, with no distress signal.

“This is a tragic day in what has already been a tragic year for Malaysia,” Najib told reporters in a televised statement from Kuala Lumpur. “If it transpires that the plane was indeed shot down, we insist that the perpetrators must swiftly be brought to justice.”

Najib said he had spoken with the leaders of Ukraine and the Netherlands, who promised their cooperation. He also said that he had spoken with President Barack Obama, and that “he and I both agreed that the investigation must not be hindered in any way.” The remark pointed to concerns about evidence tampering at the crash site, which is in an area controlled by pro-Russia insurgents.

Obama and Putin also spoke about the disaster and the broader Ukraine crisis, White House officials said, and Putin expressed his condolences to Malaysia. But in a statement quoted by Russia’s RIA Novosti news agency, Putin said, “This tragedy would not have happened if there was peace in the country, if military operations had not resumed in the southeast of Ukraine.”

The United Nations Security Council scheduled a meeting on the Ukraine crisis for this morning.

Adding to Ukrainian and Western suspicions that pro-Russia separatists were culpable, Ukraine’s intelligence agency, the State Security Service, known as the SBU, released audio from what it said was from intercepted phone calls between separatist rebels and Russian military intelligence officers Thursday. In the audio, the separatists appeared to acknowledge shooting down a civilian plane.

The Ukrainian Foreign Ministry sent reporters a link to the edited audio of the calls, with English subtitles, posted on YouTube by the SBU.

U.S. intelligence

By Thursday night, U.S. intelligence analysts were increasingly focused on a theory that rebels had used a Russian-made SA-11 surface-to-air missile system to shoot down the aircraft and operated on their own fire-control radar — outside the checks and balances of the national Ukrainian air-defense network — to shoot down the aircraft.

“Everything we have, and it is not much, says separatists,” a senior Pentagon official said. “That said, there’s still a lot of conjecture.”

Russian troops, who have been deployed along the eastern Ukraine border, have similar SA-11 systems, as well as larger weapons known as SA-20s, Pentagon officials said.

Petro Poroshenko, Ukraine’s president, said he had called the Dutch prime minister, Mark Rutte, to express his condolences and to invite Dutch experts to assist in the investigation.

“I would like to note that we are calling this not an incident, not a catastrophe, but a terrorist act,” Poroshenko said.

Reporters arriving at the scene near the town of Grabovo described dozens of lifeless bodies strewn about, many intact, in a field dotted with purple flowers, and remnants of the plane scattered across a road lined with fire engines and emergency vehicles.

“It fell down in pieces,” one rescue worker said as tents were set up to gather the dead.

The carcass of the plane was still smoldering, and rescue workers moved through the dark field with flashlights.

It was unclear late Thursday whether any Americans had been aboard the flight. Russia’s Interfax news agency said there had been no Russians aboard.

In Amsterdam, a Malaysia Airlines official, Huib Gorter, said the plane had carried 154 Dutch passengers; 45 Malaysians, including the crew; 27 Australians; 12 Indonesians; nine Britons; four Germans; four Belgians; three Filipinos; and one Canadian. The rest of the passengers had not been identified.

Andrei Purgin, deputy prime minister of the Donetsk People’s Republic, an insurgent group in eastern Ukraine, denied in a telephone interview that the rebels had anything to do with the loss of the jet. He said that the rebels had shot down Ukrainian planes before but that their anti-aircraft weapons could reach only to around 4,000 meters, far below the cruising level of passenger jets.

“We don’t have the technical ability to hit a plane at that height,” Purgin said. He also did not rule out the possibility that Ukrainian forces themselves had shot down the plane.

“Remember the Black Sea plane disaster,” he said, referring to the 2001 crash of a Siberia Airlines passenger jet bound for Novosibirsk from Tel Aviv, which the Ukrainians shot down by accident during a military training exercise.