United States of America.
"Notwithstanding the League of Nations (and Notions) Uncle Sam is still working his Thinking-box hard over trifles like this." states an intertitle. Shot of two men on a strange amphibious vehicle which has a cannon attached to it. The boat is steered through a river past the camera. One man seems to be in military uniform, the driver is in mufti.
High angle shot of the small tank like vehicle being driven up the banks of a river. C/U of the man in uniform pointing to the strange curved funnel of the vehicle. "It's a tank-cum-submarine, and finding him is going to provide a lot of worry for the enemy gunners..." L/S of a man running into the river where the very top of the vehicle is just visible on top of the water. He lifts up a seat and drives the tank out of the water. He drives it past the camera. M/S of a group of men watching the tank being driven out of the water and up the river bank.
Was a Pathe Pictorial item I think.