An international summit on nuclear security has concluded in Washington with a pledge to eliminate or safeguard all vulnerable nuclear materials within four years. President Obama announced the goal during his closing remarks.

President Obama: “I am very pleased that all the nations represented here have endorsed the goal that I outlined in Prague one year ago: to secure all vulnerable nuclear materials around the world in four years time. This is an ambitious goal, and we are under no illusions that it will be easy, but the urgency of the threat and the catastrophic consequences of even a single act of nuclear terrorism demand an effort that is at once bold and pragmatic, and this is a goal that can be achieved.”

The final statement from the forty-seven-nation summit also outlines a voluntary action plan to combat nuclear terrorism and promises greater efforts to block non-state actors from developing nuclear weapons. But it glosses over whether to continue making weapons-grade uranium and plutonium and offers no legally binding commitments for enforcement.

Obama also discussed Iran, which wasn’t invited to the summit. Obama says the US will continue to push for a new round of sanctions over Iran’s nuclear activities.

President Obama: “With respect to sanctions, I think that we have a strong number of countries on the Security Council who believe this is the right thing to do. But I think these negotiations can be difficult, and I am going to push as hard as I can to make sure that we get strong sanctions that have consequences for Iran as it’s making calculations about its nuclear program and that those are done on a timely basis.”

There are reports the US is seeking to win China’s support for sanctions by assuring it of continued oil supplies and even drilling rights in the Persian Gulf in the event Iran cuts off oil shipments. In an interview with Iranian state television, Iranian President Mahmoud Ahmadinejad criticized Obama’s stance but said Iran remains open to talks.

Iranian President Mahmoud Ahmadinejad: “We are ready to talk to and to cooperate with them, if our rights, independence and honor are respected. Acknowledging Iran will benefit both sides. As far as Iran is concerned, we are not after any confrontation.”

After the nuclear summit came to a close, Obama delivered a statement on the status of peace talks between Israel and the Palestinian Authority. Obama said he is frustrated by the slow pace of negotiations, but appeared to pin equal blame on both sides for the impasse.

President Obama: “I know that even if we are applying all of our political capital to that issue, the Israeli people, through their government, and the Palestinian people, through the Palestinian Authority, as well as other Arab states, may say to themselves, we are not prepared to resolve this — these issues, no matter how much pressure the United States brings to bear. And the truth is, in some of these conflicts, the United States can’t impose solutions unless the participants in these conflicts are willing to break out of old patterns of antagonism.”

Obama made no mention of Israel’s refusal to halt settlement construction in occupied East Jerusalem. The Obama administration has said it opposes the settlements, but has refused to propose cutting any of the billions of dollars in annual US aid to Israel.

The Israeli government, meanwhile, is accusing Syria of transferring long-range Scud missiles to the Lebanese group Hezbollah. Syria denies the allegation and says Israel is trying to divert attention from its settlement building and foil the Obama administration’s plan to reappoint a US ambassador to Syria for the first time in five years.

At least 400 people have been killed and thousands more wounded in an earthquake in China’s western Qinghai province. Most of the homes near the epicenter of the quake have reportedly been destroyed or are on the verge of collapse. The US Geological Survey registered the magnitude of the quake at 6.9.

First Lady Michelle Obama made an unannounced visit to Haiti on Tuesday along with Jill Biden. Obama and Biden toured a center for child victims of the January earthquake camp as well as a camp for the displaced. Appearing with Haitian President René Préval, Obama said she had brought a message of solidarity for Haiti.

First Lady Michelle Obama: “My husband, the President, asked that we remind President Préval and the people of Haiti that we are going to keep standing with them. That is for sure. So I repeated to President Préval the pledge that my husband made to him at the White House during his visit last month. That is, as Haiti recovers and rebuilds, you will have a steady and reliable partner in the United States of America.”

It was Michelle Obama’s first solo international trip as First Lady. The trip continues in Mexico today.

The White House, meanwhile, has announced President Obama will fly to Poland this Sunday for the funeral of President Lech Kaczynski. The Polish president was killed along with ninety-five others in a plane crash in Russia on Sunday. They had traveled to Russia to commemorate the 1940 massacre of over 20,000 Poles by the Soviet Union secret police.

In Brazil, a Brazilian rancher has been convicted of ordering the 2005 murder of the American nun Dorothy Stang. Stang spent thirty years in Brazil trying to prevent ranchers from taking the land of poor Amazon farmers. On Tuesday, the rancher, Vitalmiro Moura, was found guilty of organizing Stang’s killing and sentenced to thirty years in prison. Another rancher accused in Stang’s death is set to go on trial later this month.

The International Committee of the Red Cross says eight staff members have been kidnapped in the Democratic Republic of Congo. The group were seized by an armed group on Friday in the South Kivu region.

In Indonesia, the environmentalist group Greenpeace says it’s been the target of a suspected arson. A Greenpeace “Climate Defenders Camp” was heavily damaged by a fire this weekend on the western Indonesian island of Sumatra. Greenpeace says the fire appears to have been set deliberately. In a statement, Greenpeace said, “If this act was meant to stop our efforts to protect rainforests in Indonesia, it will not succeed.”

Back in the United States, Defense Secretary Robert Gates continues to reject calls for a probe into the US military’s indiscriminate killing of twelve Iraqis despite video capturing the attack on tape. Last week, the watchdog website WikiLeaks released a classified US military video showing a US helicopter gunship firing on Iraqi civilians in 2007. Gates has staunchly defended the servicemembers involved, claiming they were involved in a “combat” and “split-second” situation. On Tuesday, Gates criticized WikiLeaks for releasing the video, saying, “These people can put out anything they want, and they’re never held accountable for it. There’s no before, and there’s no after.”

In Arizona, state lawmakers have approved what’s being described as the harshest anti-immigrant measure in the United States. On Tuesday, the Arizona House of Representatives voted to force police officers to determine the immigration status of someone they suspect of being an undocumented immigrant. The state Senate passed a similar measure earlier this year, and Republican Governor Jan Brewer is expected to sign it into law. At a rally outside the state legislature, Phoenix-based employment attorney David Selden said the measure will increase racial profiling.

David Selden: “The policeman on the street is placed in an unacceptable position of, in every encounter that they have with a citizen, having to try to enforce immigration laws in that context and question persons based upon a reasonable suspicion of what that person’s immigration status might be. And what that means, really, is basically it will be the public policy and law of Arizona to encourage racial profiling.”

Nebraska has enacted two new measures making it harder for a woman to obtain an abortion. On Tuesday, Republican Governor Dave Heineman signed bills that bar abortions after twenty weeks of pregnancy and require women seeking an abortion to first undergo screening for mental problems and other issues. If maintained, the restrictions will take effect in October. Pro-choice groups say the laws are unprecedented and will be challenged in court. Nancy Northup of the Center for Reproductive Rights said, “It absolutely cannot survive a challenge without a change to three decades of court rulings. Courts have been chipping away at abortion rights…This would be like taking a huge hacksaw to the rights.”

In Maryland, three Prince George County police officers are under investigation following the release of video showing them beating an unarmed student. The incident occurred after a college basketball game last month. On the video, the student, John McKenna, is seen among a crowd celebrating a victory by the University of Maryland men’s basketball team. He is rushed by three officers who beat him with their batons. McKenna was initially charged with assaulting the officers, but those charges have been dropped.

And in Florida, Democratic state senator Ted Deutch has won a special election for the House seat of retired Congress member Robert Wexler. It’s the first House race to be decided since the Democratic-controlled Congress approved the healthcare reform bill.