There is of course not a flood but currently the U.S. welcomes Japan's expanded role in Afghanistan. If Japan's role enlarges this would be an additional country adding themselves to the Coalition. Instead of losing Coalition support, the U.S. appears to be slowly building to include more nations.
Japan would add non-combat troops on the ground, nonetheless, the support and assistance of an important ally would be significant in the region.
Japan's navy currently supports the U.S.-led coalition forces with a refueling mission in the Indian Ocean. Since 911, Japan has been active as part of the “Operation Enduring Freedom - Maritime Interdiction Operations (OEF-MIO).” Japan is also a party to the interdiction of alleged weapons of mass destruction under the US-led Proliferation Security Initiative.