Korean Air (KAL) is operating more flights under a code-share agreement with Alaska Airlines.
There will be 18 additional code-share flights, says a KAL spokesman.
Eleven of these are domestic routes in the USA, while the remaining seven are routes from the USA to Canada, he says.
These include services like Seattle-Vancouver and Seattle-Calgary, says the spokesman.
With the additional flights, KAL will code-share 40 routes with Alaska Airlines.