Minimum effective range for ICBMs?

Found this;

http://www.missilethreat.com/missilesoftheworld/id.139/missile_detail.asp

“Both versions were constrained by a minimum range of 600 km (373 miles) and an accuracy of 550 m CEP.”

And this:
http://www.missilethreat.com/missilesoftheworld/id.26/missile_detail.asp

“The CSS-5 can deploy its 600 kg payload with a minimum range of 500 km (311 miles) and a maximum range of 2,150 km (1,336 miles).”

Which shows missiles do have minimum ranges, but it varies from missile to missile, assuming the references are accurate. Yes I realise the second one isnt really an ICBM, but I suspect the point stands.

Otara