The United States said it could not confirm reports that Ukraine had disabled vehicles in a Russian convoy inside Ukraine and warned Moscow that any intervention into Ukraine without Kiev's permission was unacceptable.
"Even as we work to gather information, we reiterate our concern about repeated Russian and Russian-supported incursions into Ukraine," White House spokeswoman Caitlin Hayden said in a statement.
More top news
The Malaysia Airlines plane vanished on March 8, 2014, while flying from Kuala Lumpur to Beijing with 239 people on board.
Michael Rotondo, 30, has been living at his parents' house for the last eight years.
The horse had unseated his rider and was running loose when presenter Hayley Moore grabbed the reins.