U.S. Secretary of State John Kerry arrived here on Saturday to seek China's help in defusing the growing tensions with North Korea. Mr. Kerry on Saturday met Foreign Minister Wang Yi. He was scheduled to meet later in the day with Chinese President Xi Jinping, Premier Li Keqiang and State Councilor Yang Jiechi. “This is a critical moment," Mr. Kerry said at the start of his Saturday meeting with Mr. Wang, adding that he hoped “two great powers, China and the United States, can work effectively to solve problems." “We are not privy to conversations between China and North Korea," a senior State Department official who is traveling with Mr. Kerry told reporters earlier this week.