The Colonel and the Kid(2002)
(The second book in the In Uniform series)
A novel by Elizabeth Ashtree
"Add an air of mystery and a young child he's raising on his own, and that man becomes irresistible. But resisting him is exactly what Captain Natalie Wentworth's career demands. As an army protocol officer, her duties- showing Colonel Viktor Baturnov around, making sure he's properly introduced to his American counterparts and getting him settled into his training program at the Pentagon call for professional detachment. Things go smoothly until Natalie learns the real reason for the colonel's visit to America. Suddenly she's embroiled in the struggle of a father to save his son. And her feelings for both could cost her dearly." This is taken from the back of the book.
Used availability for Elizabeth Ashtree's The Colonel and the Kid
January 2002 : UK Mass Market Paperback