WASHINGTON, April 20 (Xinhua) -- U.S. Defense Secretary James Mattis met Japanese Defense Minister Itsunori Onodera at the Pentagon on Friday.

The two discussed the recently released U.S. National Defense Strategy, saying "the Japanese-U.S. alliance is essential at a time where great power competition has returned."

On Democratic People's Republic of Korea (DPRK), Mattis and Onodera affirmed the importance of close cooperation among the United States, Japan, South Korea and other "like-minded" nations "in providing credible military backing to the maximum pressure campaign."

Mattis welcomed Japan's plan to review its National Defense Program Guidelines by year end.

After the last review of its national defense program guidelines and mid-term defense program in late 2013, Japan loosened its restrictions on armaments exports for the first time in half a century, drawing wide protest and opposition from regional countries and the international community.

It also introduced new principles on defense equipment transfer in April 2014, allowing Japanese firms to export weapons if their deals pass government screening and to engage in joint defense equipment development.