Ukraine crisis: Obama in Estonia ahead of Nato summit

President Obama is travelling to Estonia to assure Nato members in the Baltic region of their security and warn Russia from interfering in any of those countries' affairs.

There are concerns that Russia may attempt to exert influence, and even possibly foment unrest, in other former Soviet states.

Ukraine is not a member of Nato but Estonia, one of the Baltic states, is, and Obama has pledged that Nato will defend it from any Russian interference.

Chris Morris reports from the Estonia-Russia border, where people are watching the visit closely.