Iran has moved to seal its border with Afghanistan, sending troops and setting up electronic detection devices to spot those trying to come in.
Iranian Brigadier-General Mohammad Sanei is quoted in the Tehran press as saying there are now 24 battalions holding the line along the 900 kilometer-long frontier.
The Iranian actions come amid predictions by the United Nations that up to 400-thousand Afghan refugees could try to cross into Iran should military action take place in Afghanistan. Iran has said that it will set up refugee camps on the Afghan side of the border to deal with that influx, but won't allow the refugees onto Iranian soil.
On Wednesday, a top U-N relief official (Under-Secretary-General Kenzo Oshima) went to Tehran to plead for the border to be opened to refugees.