We are flying from SD to Atlanta to AMS to St. Petersburg airport. We have a 2 hour layover in the AMS airport before connecting to our next flight that goes to St. Petersburg. All of these flights are through Delta, although we fly on Delta's code share, KLM, on the last flight to St. Petersburg. Please tell me if the transition in AMS airport requires going through customs. In other words, what should we expect during this transition? I haven't ever been in the AMS airport before. Thanks so much!