Possible Clues:

• Maneuver
• Diplomatic protest or manoeuvre
• A move or countermove in diplomatic relations
• Manoeuvre in diplomatic relations, from French
• Diplomatic move relates to frontier river crossing
• A diplomatic initiative
• Diplomatic initiative last month, to accept Scottish river border
• Walk in time into the river for a diplomatic move
• A political initiative
• Walk into river to make a diplomatic gesture