Tropical Storm Isaac is heading through the Gulf of Mexico, threatening to batter the Gulf Coast. Federal officials expect the storm to develop into a Category 1 hurricane and make landfall on Wednesday. The storm will mark the most serious test of New Orleans’ rebuilt levees in the seven years since Hurricane Katrina. New Orleans Mayor Mitch Landrieu said the city is prepared for the storm, just as it marks Katrina’s anniversary.

Mitch Landrieu: “It is quite ironic that we have a hurricane that is threatening us on the seventh anniversary of Katrina. It is worth noting that that brings a high level of anxiety to the people of New Orleans, but I want to assure you all that there is nothing that this storm is going to bring us that we do not believe that we are prepared to handle.”

U.S. government scientists have disclosed the sea ice in the Arctic Ocean has melted to its smallest size ever, potentially signaling that the “worst-case scenario” of global warming is becoming a reality. The National Snow and Ice Data Center and the NASA space agency say the Arctic sea ice has dwindled to some 27,000 square miles less than the previous record set in 2007. The ice will likely continue to melt with several weeks of summer weather still to come. In a statement, government scientists said the melting of the Arctic sea ice “is considered a strong signal of long-term climate warming.” Speaking to Agence France-Presse, Michael Mann, the author of a major 2001 report on climate change and director of the Earth System Science Center at Penn State University, said: “This is an example that points more to the worst-case scenario side of things. There are a number of areas where in fact climate change seems to be proceeding faster and with a greater magnitude than what the models predicted.”

The environmentalist group Greenpeace has again disrupted efforts by the Russian state-owned energy giant Gazprom to drill for oil in the Arctic. On Monday, Greenpeace activists held up a ship ferrying workers to Gazprom’s Arctic drilling site by attaching themselves to the ship’s anchor chain. Gazprom is set to become the first company to produce Arctic oil through drilling operations in the Pechora Sea. On Friday, six Greenpeace activists boarded Gazprom’s main oil rig and occupied it for several hours.

An Israeli judge has cleared Israel’s military of responsibility for the killing of the U.S. peace activist Rachel Corrie. A 23-year-old college student, Corrie was crushed to death by an Israeli army bulldozer in Gaza nine years ago. She was standing in front of a Palestinian home to help prevent its demolition. Today’s ruling came in a wrongful death civil suit brought by Corrie’s family, with the judge rejecting any negligence on the part of the driver and finding that Corrie’s death resulted from “an accident she brought upon herself.” Corrie family attorney Hussein Abu Hussein denounced the verdict.

Hussein Abu Hussein: “This verdict distorts the strong evidence presented in court and contradicts fundamental principles of international law with regard to protection of human right defenders. In denying justice in [the] Rachel Corrie killing, this verdict speaks to the systematic failure to hold the Israeli military accountable for continuing violation of basic human rights.”

The ruling follows an earlier internal Israeli army investigation that also exonerated the bulldozer drivers. The Corrie family had been seeking a symbolic $1 in damages, as well as legal fees.

The Syrian government has carried out a series of air strikes around the capital Damascus, reportedly leading to dozens of deaths. Syrian activists say at least 60 people were killed in a series of bombings. The attacks came hours after a Syrian military helicopter crashed in Damascus after reportedly taking rebel fire.

In Afghanistan, the Taliban has been accused of beheading 17 people in northeast Helmand province. The killings reportedly resulted either from the victims’ attendance at a risqué party or as a punishment for being government informants. In a separate attack, Taliban fighters killed 10 Afghan soldiers. A rogue Afghan soldier also killed two U.S. troops, the latest in a string of attacks by members of the Afghan forces on the NATO occupation. NATO spokesperson Günter Katz said about a quarter of such attacks can be traced back to the Taliban.

Günter Katz: “We can clearly identify a direct insurgent connection to the attackers in about 10 percent of the cases. In other 15 percent of the cases, we suspect an insurgent link with the attacker; however, the tie cannot be definitely proven. Given these two points, our conclusion is that about 25 percent of these attacks are in some manner related to the insurgency.”

The U.S. military has lightly reprimanded troops involved in incidents that sparked deadly unrest in Afghanistan earlier this year — Marines urinating on corpses and the burning of copies of the Koran. On Monday, both the Army and Marine Corps said the servicemembers involved had received administrative punishments such as demotions or reductions in pay but no criminal charges. The burning of Korans at Bagram Air Base sparked violence that killed at least six U.S. soldiers and dozens of Afghans.

The Colombian government has announced plans to hold peace talks with the country’s largest rebel group, the Revolutionary Armed Forces of Colombia, or FARC. Speaking from the presidential palace, Colombian President Juan Manuel Santos said he would enter the talks mindful of seeking to avoid previous mistakes.

Colombian President Juan Manuel Santos: “Exploratory conversations have been held with the FARC to find an end to the conflict. I want to make very clear to Colombians that the approaches that have been carried out and the ones that will happen in the future will be carried out within the framework based on these principles: We are going to learn from the mistakes made in the past so that they are not repeated; second, any process must lead to the end of the conflict, not its prolongation; third, operations and military presence will be maintained across the entire national territory.”

The negotiations are expected to be held in a different country, such as Cuba or Norway. Santos reportedly discussed the prospect of peace talks with Venezuelan President Hugo Chávez and former President Fidel Castro earlier this year. Following Santos’ announcement, Colombia’s second-biggest guerrilla group, the National Liberation Army, or ELN, also said it would be willing to engage in dialogue.

Four U.S. soldiers have been charged with killing a former comrade and his girlfriend to help conceal the existence of a militia they had formed to carry out anti-government attacks. Prosecutors in Georgia say the soldiers spent $87,000 on guns and bombing materials for a plot that included taking over their base, Fort Stewart; bombing a dam and poisoning the apple crop in Washington state; and ultimately overthrowing the government and assassinating President Obama. The soldiers called themselves F.E.A.R., short for Forever Enduring Always Ready. They are accused of killing former soldier Michael Roark and his 17-year-old girlfriend, Tiffany York, last December in a bid to keep their plans secret. It is the most high-profile case to involve extremism in the U.S. military ranks since neo-Nazi Army veteran Wade Michael Page killed six worshipers at the Oak Creek Sikh temple in Wisconsin and critically wounded three others before being shot dead earlier this month.

A Maryland teenager was critically wounded on Monday in a shooting at a high school in Baltimore County. The shooter was reportedly 15 years old. Monday marked the school’s first day of classes.

The lifelong peace activist Sister Anne Montgomery has died at the age of 85. Montgomery took part in a number of Plowshares disarmament protests and spent more than three years in prison for taking part in antiwar civil disobedience.