The U.S. ambassador to Japan urged Tokyo on Friday to consider taking on more responsibilities in missile defense, and called for international cooperation in inspecting North Korean cargo to prevent proliferation of weapons technology, REPORTED AP. The U.S. and Japan are developing a joint missile defense system to counter the threat posed by North Korea. Earlier this month, Washington deployed Patriot Advanced Capability-3 missiles to the southern Japanese island of Okinawa. But Japan's pacifist Constitution, which bans the use of force in solving international conflicts, means it's not clear how far Tokyo can contribute to the defense program _ for example, by shooting down a North Korean missile that might not be heading to Japan. «The United States would like an answer to whether a Japanese destroyer would shoot down that missile,» Ambassador Thomas Schieffer said. «The answer will be absolutely critical to the function and future of our alliance.» Tokyo and Washington are in the midst of reorganizing the 50,000 U.S. troops across Japan to give Tokyo more responsibility for its defense. Japan's Parliament is also debating a bill that would upgrade the Defense Agency to a ministry to boost its status within the government and put it in a better position to negotiate for funds. Japan is also trying to raise its stature overseas, sending troops to Iraq to assist U.S.-led operations there _ its most significant military deployment since World War II. Prime Minister Shinzo Abe has pledged to take steps toward amending Japan's Constitution to pave the way for more overseas missions. Speaking to reporters in Tokyo, Schieffer also urged nations to cooperate in implementing a U.N. Security Council resolution passed after North Korea's nuclear weapons test on Oct. 9 which calls for inspections of all cargo to and from North Korea to prevent any trafficking in nuclear weapons or ballistic missiles. There has been disagreement between nations on how far those checks should go, with China balking at the prospect of halting and searching North Korean ships _ saying that could provoke a battle on the high seas. «If there are containers coming out of North Korea, we'd like to have those containers inspected, whether in Hong Kong or Japan,» Schieffer said. «We need to approach enforcing sanctions in a multilateral way.» Schieffer defended Washington's refusal to hold bilateral talks with North Korea, accusing it of trying to «divide a united international community,» and urged the North instead to return to six-party talks on its nuclear ambitions. He also said there was no room for negotiation on U.S. financial restrictions imposed on North Korea over alleged counterfeiting and money laundering activities. «I can't see any government negotiating the counterfeiting of its currency,» Schieffer said. «That's not for negotiation.»