Protests continued in China Monday after a weekend of violent demonstrations over Japan's purchase of a group of islands that both countries claim as their own.<br/> <br />People gathered in front of the Japanese embassy-- it's walls stained with egg and vegetable juice from demonstrations a day earlier.<br/> <br />Sunday Chinese protesters clashed with police-- burning Japanese flags and chanting anti-Japanese slogans.<br/> <br />The protests were sparked after Japan announced last week it was buying a group of islands-- known as Senkaku in Japanese, and Diaoyu (dee-owe-you) in Mandarin-- from a private Japanese owner. Both countries are interested in the islands for their potentially valuable gas reserves.<br/> <br />U.S. Secretary of Defense Leon Panetta, who is in Tokyo with Japanese defense ministers has urged both sides to remain calm.<br/> <br />(SOUNDBITE) (English) U.S. SECRETARY OF DEFENSE LEON PANETTA SAYING:<br/> <br />"Obviously ah we're concerned by the demonstrations and we're concerned by the conflict that is taking place over the Senkaku islands. And the message that I've tried to convey, is a message that we have to urge calm and restraint, on all sides."<br/> <br />The U.S. has said they will not take an official position on matters of sovereignty-- although they are militarily aligned with Japan.<br/> <br />Panetta will head to Beijing for more meetings later today.