JIM LEHRER: In other news today, thousands of Chinese paramilitary troops moved to stop ethnic bloodshed in the country's northwest. At least 156 people have been killed in Xinjiang province since Sunday. The violence pits Han Chinese -- the country's majority group -- against the Uighurs, a Muslim minority.
We have a report from Lindsey Hilsum of Independent Television News.
LINDSEY HILSUM: Marching through the streets of Urumqi, the People's Liberation Army. Their job now: to restore peace in the Xinjiang capital.
Troop carrier after troop carrier drove between the high rises, a huge show of force meant to quell even the thought of further unrest. People looked on as a reported 20,000 soldiers, paramilitaries, and riot police, many fully armed, fanned out across the city, guarding buildings and intersections.
They blocked roads, ready to use overwhelming force to stop groups of ethnic Uighurs and Han, armed with makeshift weapons, from confronting each other for a fourth day.
Security forces gathered on People's Square in the center of the city. The Chinese government sees the trouble in Xinjiang as a threat to the stability not just of the oil-rich region, but the entire nation. Punishments will be severe.
LI ZHI, Urumqi Communist Party leader: As for those who brutally killed other people in the riot, the government will execute them.
LINDSEY HILSUM: President Hu Jintao abandoned the G-8 summit in Rome, flying back to Beijing this morning, an unprecedented move for a government which carefully nurtures its international image of stability.
More than a thousand people have been injured, some now recovering at the Urumqi People's Hospital. This Han woman, beaten by a Uighur mob, says she's lost her husband.
HAN WOMAN (through translator): My aunts have been going round all the hospitals searching for him. He must be unconscious; he's not amongst those who are conscious. They've been to the emergency wards but can't find him.
LINDSEY HILSUM: In the Uighur quarter, the walking wounded. The government hasn't said how many of each ethnicity were killed or injured. People were showing reporters video footage of yesterday's attacks by Han against Uighurs.
UIGHUR MAN (through translator): They came to kill people. I was wounded. They came to our neighborhood looking for Uighurs. They hit and chopped. People are dead. We didn't do anything. People were here studying. Some were in this mosque. What they meant was, "All Uighurs should be killed."
LINDSEY HILSUM: The heavy security presence may enforce calm, at least for the moment, but the ethnic rifts in China's far west have been exposed, and it's not clear if the government has any other policies to deal with the anger and resentment which have been ignited.
JIM LEHRER: In addition to sending in troops, Chinese authorities have sharply curtailed cell phone and Internet service in the riot zone. Government censors are also deleting videos and text updates on the violence from social networking Web sites.
North Korean leader Kim Jong-il has appeared in public again for the first time since April. It was only the second time since he apparently suffered a stroke last year. Kim is 67 years old. He looked frail as he marked the 15th anniversary of the death of his father, Kim Il-sung. The elder Kim founded the communist North Korean state.
In Pakistan, intelligence officials reported U.S. missile strikes by drone aircraft killed at least 45 militants. It was the latest barrage in South Waziristan, near the Afghan border. The region is a stronghold of the Pakistani Taliban leader.
And in Afghanistan, a U.S. soldier was killed in the western part of the country, and a British soldier died in the south. Seven British troops have been killed in the last week.
Police in Iran have now released most of the people arrested during protests last month. The announcement came today. At least 1,000 Iranians were detained after a disputed presidential election.
Overnight, President Ahmadinejad insisted his new government is legitimate. He gave his first nationally televised address since the vote.
MAHMOUD AHMADINEJAD, president, Iran (through translator): In the recount of the votes, no fault was discovered, and basically those who had claims couldn't even provide one document as proof of fraud in the election. The whole nation understood this, although we don't expect ordinary people to provide proof, but it is not acceptable from those who claim to be politicians.
JIM LEHRER: While the speech was underway, people across Tehran took to their rooftops to shout defiance. Such protests have been a nightly ritual in the Iranian capital.
In U.S. economic news, the price of oil dropped sharply again. It's down 18 percent in just over a week. Today, oil closed just above $60 a barrel in New York trading; that's after the government reported growing supplies of unused gasoline.
And on Wall Street, the Dow Jones Industrial Average gained more than 14 points to close at 8,178. The Nasdaq rose 1 point to close at 1,747.
President Obama has nominated Dr. Francis Collins to head the National Institutes of Health. Collins led the Human Genome Project that helped map the human genetic code. A White House announcement today called him "one of the top scientists in the world." His nomination is subject to Senate confirmation.
British scientists claimed a breakthrough today, creating human sperm from embryonic stem cells. The researchers reported the advance in the journal Stem Cells and Development. They said it could lead to helping infertile men have children. A number of other scientists challenged the findings; they said it's unclear normal sperm cells were actually created.