Japan had not informed its ally, Germany, in advance of the attack, although the Japanese ambassador had informed the German Foreign Minister, Joachim von Ribbentrop, at the beginning of December that relations between the US and the Japanese Empire were at a breaking point, and that war was imminent. He was instructed to ask Germany for commitment to declare war under the terms of the Tripartite Pact should that occur. Hitler and Ribbentrop had been urging Japan to attack and take over Singapore from the British, on the theory that doing so would not only hurt the UK, but would also serve to help keep the US out of the war.[3] On 28 November 1941, Ribbentrop gave confirmation to Hiroshi Oshima, the Japanese ambassador to Germany, what Hitler himself had told Japanese foreign minister Yosuke Matsuoka, that if Japan got involved in a war with the US, Germany would enter the war on Japan's side.