Saudi Arabia is building a giant border fence to seal off its troubled frontier with Yemen, Saudi border authorities have told the BBC.

BBC: Saudi Arabia builds giant Yemen border fence

Yet there are some who question the entire premise of attempting to seal the border.

ECONOMIST: The Republicans are fretting about a disappearing problem

As Kosovo, the Serbian province with an ethnic-Albanian majority, slides towards war, the government of Albania proper is begging the western defence club to help seal its border.

ECONOMIST: Why Albania feels lonely

Over the past month, Iran has drafted in 30, 000 extra police and soldiers to its eastern provinces to help seal the border against the expected flood of new refugees (see article).

ECONOMIST: Iran and Afghanistan

Mr. Bush has said Syria must seal its eastern border with Iraq to prevent the aiding of insurgents there and stop its efforts to undermine the government of its western neighbor, Lebanon.

NPR: Bush Takes Different Tack on Iraq, Troop Levels

American forces will soon seal off Baghdad from the Syrian border.

ECONOMIST: Syria hates the war, but is too weak to play the spoiler