At their late-August summit, former Prime Minister Shigeru Ishiba and Indian Prime Minister Narendra Modi adopted a suite of documents signaling their nations’ intent to increase cooperation across security and economic domains. Chief among these was the “Japan-India Joint Vision for the Next Decade," a by the two leaders outlining a 10-year roadmap for bilateral cooperation.

Yet this agreement comes at a moment of heightened uncertainty for India. Since May, New Delhi’s relations with Washington have deteriorated sharply, eroding India’s international position and placing unprecedented strain on “the Quad,” a diplomatic partnership between Japan, India, Australia and the U.S. committed to fostering a free and open Indo-Pacific.

The once-routine Quad leaders’ summit in New Delhi, planned for this autumn, wasn’t held — raising fundamental questions about how a “half-cracked” Quad will shape Japan-India defense cooperation in the decade ahead and how Tokyo should respond.