Other well-known North Korea tour operators, including Koryo Tours, founded by British expatriates in Beijing, and Uri Tours, with offices in New Jersey and Shanghai, said this week that they were "reviewing" their policies for American citizens ahead of a possible travel ban that has been mooted by U.S. Secretary of State Rex Tillerson.
Chinese Foreign Ministry spokesman Geng Shuang called Warmbier's death a "tragedy." He told reporters at a daily news briefing that he hopes Pyongyang and Washington could communicate over related issues.
China, North Korea's longtime communist ally and biggest source of economic and diplomatic assistance, provides the largest numbers of tourists to the country by far.
Warmbier was among the estimated 5,000 non-Chinese who visit North Korea every year on packages that often include trips to Pyongyang, the capital, as well as the demilitarized zone separating the two Koreas, Mount Paektu and sometimes the Masik ski resort. Americans comprise about a fifth of all non-Chinese tourists to North Korea, tour operators say.
Young Pioneer Tours, which was founded by British expatriate Gareth Johnson, said that it was denied any opportunity to meet with Warmbier after his detention, and that the way it was handled was "appalling."
"There has still been almost no information disclosed about his period in detention," the company said in its Facebook statement. "Considering these facts and this tragic outcome we will no longer be organizing tours for U.S. citizens to North Korea."
The travel agency specializes in North Korea tours and is based in the central Chinese city of Xi'an. It also offers tours to Iran, Turkmenistan and the Chernobyl nuclear disaster site in Ukraine, among other locations.
Warmbier was sentenced to 15 years in prison with hard labor, convicted of subversion after he tearfully confessed he had tried to steal a North Korean propaganda banner.
The University of Virginia student was held for more than 17 months and medically evacuated from North Korea last week. Doctors said he returned with severe brain damage, but it wasn't clear how that occurred.
Three other Americans are still imprisoned in North Korea, accused of crimes against the Pyongyang regime. The U.S. government says North Korea is using such detainees as political pawns. North Korea accuses Washington and South Korea of sending spies to overthrow its government.
The administration of President Donald Trump has been pushing China hard to use its influence with North Korea to curtail its development of nuclear weapons and ballistic missiles.
While Beijing may attempt to use such leverage to free Americans in the North, its influence is limited, said Jin Qianyi, a professor at Yanbian University's Institute of Northeast Asia Studies, which sits along the border with North Korea. Beijing also needs to ensure it maintains channels of communication with Pyongyang, whatever their differences, Jin said.
"I personally believe that it is not possible for China to step up sanctions against North Korea because China has already been tough. How much tougher can it be?" Jin said.