The Obama administration is warning Japan over talk of scaling back military ties to the United States. In the past week, Japan has announced it would pull out of a refueling mission in the Indian Ocean in support of US-led military action in Afghanistan. Japan also wants to renegotiate a military agreement on relocating a US Marine base inside its borders. The ruling Democratic Party of Japan was elected in August on a platform that included revisiting Japan’s US ties. On Wednesday, Defense Secretary Robert Gates held talks with Japanese officials in Tokyo, where he urged them to “move on” from talk of reevaluating existing military agreements. Gates’s comments come as a State Department official told the Washington Post that Japan is becoming a major challenge for the US in Asia, saying, “The hardest thing right now is not China, it’s Japan.”