New Delhi, May 12 -- President Donald Trump on Tuesday is set to leave for Beijing to meet with President Xi Jinping after weeks of trying, and failing, to persuade the Chinese government to use its considerable leverage to prod Iran to agree to U.S. terms to end the two-month old war - or at the very least, reopen the critical Strait of Hormuz.

Trump has veered between venting that China, the world's biggest buyer of Iranian oil, hasn't done more to get the Islamic Republic in line, and acknowledging that Xi's government helped de-escalate the conflict last month by nudging Tehran back to ceasefire talks when negotiations wobbled.

But ahead of the U.S. leader's high-stakes visit, the White House has set low expectations that Trump will...