In high-level civil aviation talks that got under way Tuesday in Washington, the United States made fresh demands that Japan let "nonincumbent" U.S. carriers offer 56 more flights a week through regional airports in Japan, Transport Ministry officials said Wednesday.The two sides had already agreed to give the nonincumbent carriers, whose operations are limited under the existing agreement, 90 flights a week -- 70 plus 20 more transferred from rights currently held by incumbent carriers. The new demand by the U.S., which wants 56 more flights on top of that, is "unacceptable" to the Japanese side, according to the officials in Tokyo."Both sides gathered with strong expectations of an agreement this week, but it now feels as though an agreement is moving farther away as we actually start the negotiations," a Japanese negotiator reportedly said in Washington. In contrast with nonincumbent carriers, the incumbents -- Northwest Airlines, Inc., United Airlines, Federal Express Corp. and Japan Airlines -- enjoy greater aviation rights in the trans-Pacific market.The negotiators are trying to hammer out a framework for a four-year transitional agreement in an effort to further liberalize the trans-Pacific market during the seventh official vice-ministerial aviation talks. In addition to granting more aviation rights to the nonincumbent carriers, negotiators spent the first day discussing the so-called safety net issue and same-country code-sharing, the official said.Although the two countries will start negotiations in about three years to cover the future after the four-year transitional agreement expires, the safety net is being designed in case the two governments fail to reach the next accord. Meanwhile, the U.S. is demanding that Japan accept same-country code-sharing, which enables two carriers based in the same country to jointly operate on the same route.Japan insists that joint operation be allowed only for exceptional cases, saying that if same-country code-sharing is fully allowed, powerful American carriers can team up for the joint operation and disrupt fair competition. As the two countries move toward the last stage of the prolonged negotiations, pressure to finalize the transitional accord is mounting and those who are trying to prevent them from reaching an accord are intensifying their actions, according to Japanese sources.