TOKYO (AP) — Japanese Prime Minister Shinzo Abe pledged Sunday to bolster his country’s role under its security pact with the U.S. in “outer space and cyberspace,” as the allies marked the 60th anniversary of a treaty that has been the basis for their postwar defense alliance.

Abe’s grandfather, Nobusuke Kishi, who was prime minister at the time, signed the treaty in Washington on Jan. 19, 1960, with President Dwight Eisenhower. The treaty allows for the stationing of tens of thousands of U.S. troops and the deployment of American warships in Japan. In exchange, the U.S. is obligated to protect Japan in case of enemy attack.

“We have elevated the relationship to one in which each of us, the U.S. and Japan, protects the other, thereby giving further force to the alliance,” Abe said in his opening remarks. “Going forward, it is incumbent upon us to make it even more robust, to make it a pillar for safeguarding peace and security in both outer space and cyberspace.”

The anniversary comes as Washington adds pressure on Japan to shoulder more of the financial cost and play a greater defense role in the Asia-Pacific region to make up for a receding U.S. presence.

“As the security environment continues to evolve and new challenges arise, it is essential that our alliance further strengthen and deepen,” President Donald Trump said in a statement marking the anniversary. “I am confident that in the months and years ahead, Japan’s contributions to our mutual security will continue to grow, and the Alliance will continue to thrive.”

The bilateral security treaty, initially designed to facilitate a greater U.S. presence in the Asia-Pacific region as a deterrence to Soviet threats, is a legacy of the Cold War era.