The leaders of Japan, the United States, Australia and India agreed Friday to work to expand COVID-19 vaccine production for developing countries amid China's growing influence, while pursuing collaboration toward a rules-based maritime order in disputed waters.

Noting that the so-called Quad countries are united in "a shared vision for the free and open Indo-Pacific," the leaders pledged in their first-ever summit meeting that they will strengthen cooperation on "the defining challenges of our time" ranging from the coronavirus pandemic and climate change to technology and maritime issues.

"We will continue to firmly advance our cooperation to achieve ambitious and concrete results," Prime Minister Yoshihide Suga told reporters after the virtual meeting that was also joined by U.S. President Joe Biden, Australian Prime Minister Scott Morrison and Indian Prime Minister Narendra Modi.