Japan needs to take "proactive leadership" on global issues like nuclear nonproliferation and climate change and play a larger role in United Nations peacekeeping missions, Foreign Minister Katsuya Okada said Friday.

In a speech in the Diet, Okada also said Japan's alliance with the U.S. remains the cornerstone of Japanese diplomacy, despite friction over the relocation of a U.S. Marine Corps air station in Okinawa.

Speaking about Japan's participation in U.N. peacekeeping operations, Okada stressed the importance of Japan's decision to send Self-Defense Forces units to Haiti to help rebuild the earthquake-stricken nation, but said mere participation in such activities is not enough.

"Japan has made wonderful achievements in Cambodia and East Timor but it cannot be said that Japan's recent contribution is enough," Okada said. "In order to play a larger role in maintaining and building peace, I will consider further contribution in addition to the Haiti mission."

SDF dispatches for reasons other than disaster relief, however, are likely to be challenged by the Social Democratic Party, one of the ruling Democratic Party of Japan's junior coalition partners. The SDP strongly opposes SDF deployments in general due to constitutional concerns.

Okada also pointed out that Japan must display leadership in nuclear nonproliferation to create "a world without nuclear weapons," a vision put forth by U.S. President Barack Obama, who recently won the Nobel Peace Prize.

As an example, he suggested banning the use of nuclear weapons against countries without nukes and limiting the possessing of nuclear weapons to deterrence.

Despite tensions with the U.S. over the relocation of Futenma Air Station, Okada followed the example of past foreign ministers by repeating that the Japan-U.S. alliance is the cornerstone of Japan's diplomacy.