What sounds in American English are the most difficult for you to pronounce?

If you speak American English as a second (or third) language, what sounds are the hardest for you to say? For example, is it our "th" sound, our "sh" sound, a particular vowel, or some other sound? Please indicate your native language or dialect and native country.

This is a serious inquiry, and your comments are appreciated!

Business Speech Improvement provides intensive, customized training in American English pronunciation, presentation skills, general diction, executive communication, lip-reading, idea generation strategies and more. Additional information can be found at www.BusinessSpeechImprovement.com.