"There are no plans at the moment to publish SHOOT TO KILL in the US, so a British copy would be your best way forwards."
This is not to say there will never be a U.S. print edition, but at the moment there appears to be no U.S. publisher on board.
The good news is the UK edition can be purchased on Amazon.co.uk at a 46% discount. Even with shipping, the end price isn't all that different from what a U.S. edition would cost. Also, The Book Depository currently has the UK edition for $16.29 with free worldwide shipping. You can also find new and used copies via the U. S. Amazon Marketplace.
Thanks to Derrick for bringing us this news.