By Philip Blenkinsop BRUSSELS, Jan 21 (Reuters) - U.S. customs authorities will face a real challenge if President Donald Trump goes through with his threat to place tariffs on six EU countries - rather than the whole European Union - given the ease of movement of goods between EU members.

The European Union is preparing to activate a long dormant package of retaliatory tariffs on American products, with implementation penciled in for Feb. 7 if diplomacy fails. The move would escalate a fast moving confrontation with Washington over Greenland policy and trade leverage,

Boeing aircraft, bourbon, motorcycles and soyabeans among targeted products if Donald Trump makes good on his threats

Once signed, and ratified by the European Parliament, a process that could take at least a year, ‌the pact could expand bilateral trade, and lift Indian exports such as textiles and jewellery, which have been hit by 50% U.