The intermediary approached by the Japanese was U.S. President Theodore Roosevelt, who had publicly expressed a pro-Japanese stance at the beginning of the war. However, as the war progressed, Roosevelt had begun to show concerns on the strengthening military power of Japan and its long-term impact on U.S. interests in Asia. In February 1905, Roosevelt sent messages to the Russian government via the US ambassador in Saint Petersburg. Initially, the Russians were unresponsive, with Tsar Nicholas II still adamant that Russia would eventually prove victorious. The Japanese government was also lukewarm to a peace treaty, as Japanese armies were enjoying an unbroken string of victories. However, after the Battle of Mukden, which was extremely costly to both sides in terms of manpower and resources, Japanese Foreign Minister Komura Jutarō judged that it was now critical for Japan to push for a settlement.