North Korea snubbed senior Chinese diplomats this month as tensions mountedwiththe U.S., according to people familiar with the situation, raising questions about the influence Beijing's leaders have over Kim JongUn.

Pyongyang didn't respond to requests fromChina ForeignMinister Wang Yi and Wu Dawei, the country's top envoy for North Korean nuclear affairs, to meet with their North Korean counterparts, according to the people, who asked not to be identified because the discussions were private. The overtures came after Chinese President Xi Jinping met with his U.S.counterpartDonald Trump in Florida, the people said.

Trump has sought to pressure Xi into taking stronger action to help stop Kim's regime from developing more advanced nuclear weapons and ballistic missiles. While North Korea relies on China for most of its food and fuel, ties between the allies have been frosty under Xi: Since taking power in 2012, he hasn't met Kim face to face.

It's unclear how often Chineseofficialsrequest to visit North Korean counterparts, and how often they don't get a response. China's foreign ministry didn't immediately respond to faxed questions.

Wu, special representative for Korean Peninsula Affairs, met last week with his South Korean counterpart in Seoul to discuss North Korea's advancing nuclear and missile programs. He had planned to go to Pyongyangafterward butNorth Korea didn't answer his request, Yonhap News reported, citing an unidentified diplomatic source in Seoul.

Wang, China's foreign minister, had urged the U.S.andNorth Korea to dial down tensions last week, comparing the situation to a "storm that is about to break." China wants both sides to resume negotiations over North Korea's nuclear program that collapsed in 2009.

High-level dialogue between North Korea and China was cut back after the 2013 execution of Kim's uncle, Jang Song Thaek, who was an advocate for Chinese-style economic reform and had been the major go-to person forleadersin Beijing. Jang's wife had raised Kim Jong Nam, the half-brother of Kim JongUn whowas murderedwitha chemical agent earlier this year at an airport in Malaysia. He had been living under Chinese protection.

China in February banned coal imports from North Korea after the murder, leading to a rare public spat after Pyongyang accused Beijing of "dancing to the tune of the U.S." Last week, the Global Times, a Communist Party-affiliated newspaper, argued that Beijing should support stiffer sanctions against North Korea, including the limit of oil exports, if the country conducts another another nuclear test.

Trump said on Sunday that he refrained from labeling China a currency manipulator in part because of the country's help in dealing with North Korea. During a visit to South Korea, Vice President Mike Pence said on Monday that he was "heartened" by recent moves from China on North Korea and urged more action a day after Kim conducted a ballistic missile test.

Trump acknowledged the difficulty China faces with North Korea after meeting Xi, telling the Wall Street Journal last week: "After listening for 10 minutes, I realized it's not so easy." Last week he also told reporters that he thought Xi "means well and I think he wants to help."

No one from China appearedata military parade in Pyongyang to mark the 105th birth anniversary of Kim's grandfather, the nation's founder, last weekend.

In addition to government interaction, officials from the ruling parties of China and North Korea have regularly met in the past. The last senior Chinese official to visit Pyongyang was Liu Yunshan, a member of China's Politburo Standing Committee, who attended a Workers' Party celebration in North Korea in October 2015.