The United States and its Western allies have accused the People's Republic of China, one of the five permanent members of the U.N. Security Council, of failing to use its influence in Sudan to help end what many have called genocide.
In the past, China has blocked attempts by the Security Council to place sanctions on Khartoum and on members of Sudan's government involved in the atrocities, and has refused to speak out against the government's role in the mass killings. The Sudanese government has denied involvement in the fighting.
During a July 2004 Security Council consideration of a U.N. resolution demanding Sudan prosecute Arab militia members accused of atrocities, the Chinese ambassador worked to water down the measure, striking down a more forceful version that specifically threatened Khartoum with sanctions.
But following presidents Hu's and Bush's meetings, China appeared to relent somewhat, choosing Tuesday to abstain, rather than follow through on an earlier veto threat, in a vote to impose economic and travel sanctions on four individuals accused of playing a role in the regional violence.
Analysts point to three main reasons for China's continued unwillingness to cooperate with international efforts in the restive western Darfur region. The rising Asian economic superpower has significant business interests in Sudan having invested an estimated $10 billion in Sudan since the 1960s, according to the Council on Foreign Relations. The country of 1.3 billion people also has a growing thirst for oil and Sudan provides up to 10 percent of that oil, making China Sudan's largest trade partner. And on the political front, analysts point to China's longstanding policy of refusing to meddle in the affairs of other governments for fear its own practices could be scrutinized.
"One of the problems is that the Chinese government has been subjected to similar pressure," said George Mason University professor Ming Wan, who was born in Beijing and is the author of "Human Rights in Chinese Foreign Relations: Defining and Defending National Interests." "In effect it doesn't want the U.N. to have any sanctions on countries for human rights reasons. It itself is vulnerable."
Attempts to reach the Chinese mission to the United Nations in New York about the government's policies in Sudan failed.
But beyond the desire to steer clear of Sudan's internal issues, China's economic relationship with Sudan runs deep.
China's state-owned China National Petroleum Corp. is the largest foreign investor in Sudan's oil sector, according to Brookings Institution China Energy Fellow Erica Downs. The country's Greater Nile Petroleum Operation Co. is the largest overseas project for any Chinese firm in terms of production.
China owns oil fields in and around Darfur, buys 70 percent of Sudan's oil and allegedly has helped finance manufacturing facilities in Sudan used to build weapons, according to a 2003 Human Rights Watch report.
"They've built pipelines. They've invested maybe a billion dollars in upgrading the Khartoum refineries. Chinese companies are building the Merowe Dam. There's a lot of activity going on," Downs said.
China, Downs said, is now stuck in a situation where it does not want to lose the capital it has invested in Sudan but is uneasy with Khartoum's Darfur policy.
"They need oil, they want the oil. I don't necessarily get the sense that the Chinese government is enamored with Khartoum or actively endorses what's being done in Darfur," Downs said. "All things considered I'm sure the Chinese government wishes this would go away."
According to Downs, China's need for energy coupled with its political policies on sovereignty explain its actions on the Security Council.
"There's been a longstanding opposition in China against international sanctions as a tool to influence other governments, long before China was an energy consumer," Downs said. "Even if China wasn't heavily invested in Sudan's oil sector, I don't know that we'd necessarily see them spearheading the effort to impose sanctions on Sudan."
But some nongovernmental organizations have said that China's relationship with Sudan can be found on the battlefields of Darfur. On a recent trip to Darfur, Ken Bacon, president of the nonprofit group Refugees International and a former Pentagon official, spotted evidence of Chinese weapons in use in the Darfur conflict.
"I saw rocket shells with Chinese markings on them in an area about 30 or 40 kilometers outside of El-Fasher," Bacon said.
El-Fasher, the capital of North Darfur, is home to one of the largest evacuee camps in Darfur. The area has been marked by the Janjaweed militia as a target for raping women who leave the camp in search of food and water.
Some evidence, including eyewitness accounts and media reports from Sudan, say China has supplied the country with arms in the past, but questions remain about whether that is still occurring. An unclassified CIA report from 2003 detailing international trade of ballistic missiles and nuclear, chemical and advanced conventional weapons showed that Russia had supplied Sudan with military aircraft and weapons, but detailed nothing about a Sudan-China connection.
But according to Bacon, "There is a military and arms relationship between China and Sudan. Late last year in the Sudanese press there was a story saying that Sudan was buying some jet fighters from China and that they've purchased other sophisticated military gear from China."
Human Rights Watch also supports Bacon's claim. The organization reported that as early as 1969 the Chinese government brought arms to Sudan. The group said arms sales rose in the 1990s as Sudan's civil war raged and that China sold Sudan antitank mines, ammunition, tanks, helicopters and jet fighters.
The United Nations has imposed an international arms embargo against selling to parties to the Darfur conflict, including to the Janjaweed and to the rebel groups, but no such embargo exists against selling to the Khartoum government.
"I don't mean to suggest that China is violating any embargos, but there clearly is an arms sales relationship," Bacon said.
China has remained mum about any arms deals with Sudan.
"The Chinese government doesn't talk about the arms sales," Wan said. "This is very sensitive. They are quite open about economic interests, but they don't normally talk about how arms sales factor in."
Estimates show that between 180,000 and 300,000 people have died as a result of the violence in Darfur and the subsequent humanitarian crisis. Backed by the United States and the EU, the United Nations has made several attempts to end the crisis but to little avail. Seven rounds of peace talks between rebel groups and Sudan's government in the Nigerian capital of Abuja also have failed to end the conflict.
And, as recently as April, the Chadian government accused the Sudanese government of backing militias crossing the border into Chad, carrying out attacks on civilians and threatening to overthrow the president.
Some experts say China's relationship with Sudan could be used in an effort to ease the conflict before the situation with Chad destabilizes the region. To stop this conflict, China should take larger role in the negotiations and use its economic and diplomatic heft to influence Khartoum, argued Carolyn Bartholomew, vice chairwoman of the U.S.-China Economic and Security Review Commission, a group established by Congress in 2000.
"A lot of the concern that people have about China's role in the world is all coming to head in one place at one time," Bartholomew said.
"[Deputy Secretary of State Robert] Zoellick gave a speech months ago putting out the idea that China needs to be a responsible player. Sudan would be a real starting point to see how seriously China is going to take the concerns of the world," Bartholomew added.
But some regional experts doubt China will approach Darfur with geopolitical considerations first and foremost in its thinking, but rather with economic and energy policy.
"The Chinese government has never said you cannot invest in countries that have human rights problems. China has human rights problems as well," Wan said.
According to Wan, it may be the Darfur crisis that makes Sudan particularly attractive to China.
"It's the political situation that gives the Chinese government political and economic advantage. A typical Western firm would find it difficult to operate there and Chinese firms do not have qualms about that."
And, said Wan, China may have an added interest in keeping the Khartoum government, a government friendly to its economic advances, in power.
"If the rebel forces win, there goes the Chinese investment."