USS Panay sunk in China!

The gunboat USS Panay came under fire earlier today while evacuating civilians from the front line in the war between Japan and China, despite being clearly marked with American flags. Struck with two bombs, she sank later that day with three US citizens killed and many more wounded. Survivors were picked up by American and British gunboats in the area. Japan has been quick to claim it was an accident and offer an apology, but some think that the attack was deliberate and a number of advisors are calling for war. However, public support for war remains low and any declaration is likely to be deeply divisive. How should we respond?