To the north and west lie the Russian territories of Stavropol and Krasnodar.

BBC: Karachay-Cherkessia profile

To the east and west lie the Russian republics of North Ossetia and Karachayevo-Cherkessia.

BBC: Kabardino-Balkaria profile

South Korea's western islands are seen as especially vulnerable to attack from the North, as they lie just south of the sea border, which is disputed by Pyongyang, says the BBC's Lucy Williamson in Seoul.

BBC: South Korean prime minister visits border island

One block north lie the pre-Hispanic ruins of Templo Mayor, believed by the Aztecs to be the centre of the universe, and just a stone's throw from the site is Palacio Nacional, which houses dramatic Diego Rivera murals.

BBC: Mexico City: More than a stopover

She adds that some in Washington have talked of maybe targeting North Korean financial interests, but the only real pressure is seen to lie with China.

BBC: North Korea carries out biggest nuclear test