LONDON (AP) — If Ukrainian rebels shot down the Malaysian jetliner, killing 298 people, it may have been because they didn’t have the right systems in place to distinguish between military and civilian aircraft, experts said Saturday.

American officials said Friday that they believe the Boeing 777 was brought down by an SA-11 missile fired from an area of eastern Ukraine controlled by pro-Russian separatists. U.N. Ambassador Samantha Power said the Russians might have provided technical help to the rebels to operate the systems.