Asia - Seoul (ICN) airport - int'l connections?

Does ICN allow international transit without fully exiting and reentering the secure area?

yes, but you might be in for a bit of a walk if you're connecting from one airline to another.

http://www.airport.or.kr/Eng/guide/change/change.jsp

As pointed out by moondog, the airport has a single terminal, with nearly a mile between for instance NW gates at one end and some KE gates at the other.

Thanks for the information. I am toying with an itinerary that includes a transfer at ICN to get a cheaper business fare to Tokyo (compare USA-Tokyo business fares with USA-Seoul), or a Tokyo-Seoul-Tokyo-USA fare broken at Seoul, again for the fare break.