GRABOVE, Ukraine - The United States on Friday built a case that pro-Moscow separatists downed a Malaysian airliner in Ukraine with a surface-to-air missile, killing all 298 people on board -- with the possible technical assistance of Russians.
The first international monitors struggled to gain access to the gruesome body-strewn crash site in rebel-held eastern Ukraine as rebels ruled out a cease-fire.
Grief over the tragedy meanwhile turned to fury and vows that justice would be done, as heart-rending stories emerged of the men, women and children aboard the doomed Boeing 777.
US President Barack Obama presented the latest conclusions of US intelligence analysts about the "unspeakable" carnage.
He cranked up political pressure on President Vladimir Putin to take action, and on Europe to do more to punish his escapades in Ukraine.
"Evidence indicates that the plane was shot down by a surface-to-air missile that was launched from an area that is controlled by Russian-backed separatists inside of Ukraine," Obama said.
He avoided definitive conclusions about what exactly happened to Flight MH17, but said only a sophisticated missile could destroy a passenger jet flying at more than 30,000 feet.
He said previous attacks by separatists on government aircraft in Ukraine suggested rebels benefited from Russian technical expertise.
"A group of separatists can't shoot down military transport planes, or they claim, shoot down fighter jets without sophisticated equipment and sophisticated training, and that is coming from Russia," Obama said.
Samantha Power, the US ambassador to the UN, said the complexity of the SA-11 missile Washington believes was used in the attack would likely preclude it being solely operated by separatist forces.
Pentagon spokesman Rear Admiral John Kirby said: "It strains credulity that (the missile) can be used by separatists without some measure of Russian support and assistance."