On Friday afternoon, President Barack Obama addressed the nation in regards to the nature of the deadly attack on a Malaysian passenger plane which resulted in the deaths of nearly 300 people, what the United States knows so far, and what steps the U.S. and its allies are prepared take to address this escalation of hostilities.

Obama revealed that one American dual citizen was killed that attack by pro-Russian separatists in east Ukraine. He noted that the United States has confirmed that a surface-to-air missile was fired from rebel-held areas of Ukraine at the plane, resulting in the crash. “Moreover,” Obama added, “we know that these separatists have received a steady flow of support from Russia.” Much of which, he said, included financial and logistical support, as well as the transfer of sophisticated weaponry.

The president added, however, that many details of that attack were not yet known and that it was important not to rush to judgment. He stopped short of saying what steps the United States would take in order to address this escalation of tensions.

The president added that a thorough and impartial investigation into this incident was important, and that the evidence at the crash site must not be tampered with (something which may have already happened). That may prove difficult given the fact that pro-Russian separatists responsible for this attack, who the president claimed are provided with material support from Russia, were reportedly shooting at European investigators as Obama spoke.

The president opened his speech forcefully, but quickly reverted to lawyerly caveats in order to avoid presenting for the world an indictment of Russia over their clear culpability in this gross violation of human rights. The behavior of the separatists thus far suggests that Moscow does not take the president seriously.

UPDATE: The OSCE could not confirm whether investigators were shot at by pro-Russian rebels, but the organization’s chairman said investigators’ access to the site was impeded:

Monitors from the Organisation for Security and Cooperation in Europe were not able to secure an access corridor on Friday to the site where a Malaysian airliner crashed in eastern Ukraine, the OSCE’s chairman said.

“They did not have the kind of access that they expected. They did not have the freedom of movement that they need to do their job. The crash site is not sealed off,” Thomas Greminger told Reuters by telephone.