WATCH: 'Is Downed Malaysian Plane Putin's Worst Nightmare?'

Reports of a 'pro-Russian separatist leader bragging' about shooting down a Ukrainian army transport early in the day leads Fox News analyst to declare 'this is Putin's worst nightmare.'

REUTERS - Ukraine's state security chief accused two Russian military intelligence officers of involvement in the downing of a Malaysian passenger plane in eastern Ukraine on Thursday and said they must be punished for their "crime".

SBU chief Valentyn Nalivaychenko said he based his allegation on intercepts of phone conversations between the two officers.

"Now you know who carried out this crime. We will do everything for the Russian military who carried out this crime to be punished," he told journalists.