Political opponents have criticized Prime Minister Yoshihiko Noda as a weak leader who easily gives in to foreign demands to avoid confrontation in territorial disputes. Others have long suggested that deep down, the prime minister was a defense hawk who wanted to see a greater role for the Japanese military.

At a lavish naval ceremony on Sunday, Mr. Noda - a son of a lifelong Self-Defense Forces soldier - delivered a speech in front of hundreds of Japanese troops that offered a glimpse of that hawkish side.

Surprising even military officials, the address included an expression used in a slogan for naval battles during the Russo-Japan War in the early 20th century. The prime minister also took the unusual step of including in his speech slogans that have been recited by Japanese naval cadets since before World War II.

"The security environment surrounding our nation has become more difficult than ever before," Mr. Noda told the troops on the destroyer JS Kurama. "We have a neighbor that launches missiles disguised as satellites and engages in nuclear development. We are facing various cases related to territory and sovereignty," the prime minister said, referring to North Korea, and to territorial disputes with China and South Korea, respectively. The prime minister was wearing a tailcoat, the designated garb for top civilian government officials at formal military ceremonies.