GANYARD: It could be in a lot of places. There's literally tens of thousands of miles of ocean that are going to have to be searched. Because we have this black hole where there's no radar data, we don't know the heading, the true altitude, the air speed, where that aircraft could go. So, it's going to take a lot of time to find that wreckage.
RADDATZ: And that black hole is why?
GANYARD: The black hole is there because the radar coverage only extends off the Malaysian coast so far and only extends off the Vietnam coast so far. So there's this gap in here. The world is a huge place. And it's not big enough to be covered by radar.
Now if you're going to fly from Europe, you're going to be scene. If you're going to fly over the North Pacific, there will be data link and satellites, but a lot of the world is not covered by radar and sometimes planes are out there alone and unafraid -- they know where they are because they have GPS. But nobody else knows until they communicate.
RADDATZ: In the past, you've told ABC -- you've kind of been dead-on on your predictions on what might have brought an airplane down. This one is so mysterious.
Does your gut tell you anything on this one?
GANYARD: It doesn't tell me anything, which I think means that we're going to have to keep the aperture open in terms of what we consider. Normally on this, I would not say that we would look at terrorism, but an airplane just does not come down or disappear at 35,000 feet. Everything is going to have to be considered. And I think terrorism we'll have to be one of those elements.
RADDATZ: And, Pierre, this could take a long, long time, even if they find the airplane.
THOMAS: Yes. They are saying they have to follow the evidence. And the key, again, is find that wreckage. They're very frustrated that they don't have any clue yet in terms of physical evidence. And the one thing I would add is that this comes against the backdrop of all those concerns about toothpaste container bombs, shoe bombs. The law enforcement and intelligence community was already keyed up and now they're more so.
RADDATZ: OK, thanks very much, Pierre and Steve.
Now to that escalating war of words between President Obama and Vladimir Putin over Ukraine. This morning, Russia tightening its grip on the strategic region of Crimea, despite warnings from the White House. ABC's Alex Marquardt is in the middle of it all in Crimea, where in just days, a critical vote will determine if the country splits apart -- good morning, Alex.
ALEX MARQUARDT, ABC NEWS CORRESPONDENT: Good morning, Martha.
These forces are part of what is believed to be a growing Russian presence. Here in Crimea this morning, their control tightening by the minute.
Of course, Russia is denying these troops are even theirs.
MARQUARDT (voice-over): On the move, large unmarked convoys of troops believed to be Russian, this weekend crisscrossing the Crimean Peninsula. The Ukraine/Crimea border reportedly now littered with land mines planted by pro-Russian forces, who, for the past three days, have blocked international military monitors from entering Crimea, even firing warning shots.
In just 10 days, Russia has seized Crimea -- border crossings, airports, government buildings and military bases, just a handful still in Ukrainian control, but surrounded.