The "stuff it in a suitcase and keep your mouth shut" importation of trees mostly disappeared after 9/11 that brought advanced imaging systems for luggage at airports and a more alert Customs and Border Protection. Good luck getting past TSA and CBP now with a plant in your suitcase. You might be successful, but the downside is extreme. International smuggling of plants is big business and both agencies are looking for it. Fines and possibly jail time--it's a federal offense (I think it's a violation of the
Lacey Act.) Fines run from a couple of hundred dollars to $10,000. Your tree will be taken and destroyed.