fresh water has been provided from the US Navy to support cooling efforts at the Fukushima Daiichi nuclear power plant. 1 May 2011 US troops will begin to withdraw from the Tohoku coastline and return to their bases, and the US-Japan Joint Cooperation Center in Sendai has closed down. While it will continue to airlift personnel and supplies as needed, the work on the ground will be handed over to the Japanese Self-Defence Forces. 4 May 2011 Marines from the Consequence Management Support Force return to Okinawa from mainland Japan 4 May, representing the departure of the last major element of the III Marine Expeditionary Force deployed to mainland in support of Operation Tomodachi. 4 September 2012 United States Department of Defense releases location-based radiation dose estimates for U.S. personnel involved in Operation Tomodachi on the Environmental Health Surveillance Registries website. Clean-up efforts US troops assisted Japanese government workers in cleaning up debris and rubble left by the tsunami. Effect on Japan–US relations The disaster may have brought a diplomatic opening to Japan. The support provided by the US illustrated the value of the relationship between the countries. It was commented that the level of support provided by the US will probably assuage tension over base relocation disputes between the two governments. The Yomiuri Shimbun reported that the "coordinated relief activities at the disaster sites are expected to deepen the Japan-U.S. alliance." On 4 April 2011, Japan's minister of defense, Toshimi Kitazawa, accompanied by US ambassador to Japan John Roos, visited the Ronald Reagan to thank its crew for its assistance as part of Operation Tomodachi. Said Kitazawa, "I have never been more encouraged by and proud of the fact that the United States is our ally." On 10 April 2011, Japan's Prime Minister, Naoto Kan, visited Camp Sendai to talk to U.S. service members. The prime minister spoke of the immediate response of the U.S. military and expressed his belief that the joint efforts between the U.S. military and the JGSDF will strengthen the bonds between the Japanese people and the United States. A nationwide survey conducted in Japan from September to October 2011 found that an all-time high of 82 percent had friendly feelings toward the US. Japan's Foreign Ministry attributed the number to the effects of Operation Tomodachi. Similarly, the Pew Research Center showed that 85% of Japanese people had a favorable opinion of the U.S. in