South Korean troops mounted a live-fire exercise near the tense border with the North on Thursday amid high tensions and in the face of Pyongyang threatening retaliatory strikes.

The one-hour exercise in Pocheon, the first of its kind this year near the land border, was a regular drill involving about 170 tanks, self-propelled howitzers, helicopters and four warplanes, a Defense Ministry spokesman told Agence France Presse.

Nine Afghan police were killed in an insurgent attack that authorities said Thursday was believed to have been facilitated by a fellow officer and suspected Taliban infiltrator.

The attack in the southern province of Uruzgan late Tuesday follows a wave of incidents in recent weeks in which members of the Afghan security forces have turned their weapons on their NATO and U.S. allies.

The U.S. State Department for the first time listed the Vatican as potentially vulnerable to money laundering, along with 67 other countries.

The department's annual International Narcotics Control Strategy report listed the Vatican as a "jurisdiction of concern" along with countries like Albania, the Czech Republic, Egypt, South Korea, Malaysia, Vietnam and Yemen.

Syria's deputy oil minister resigned on Thursday, becoming the most senior official to join the rebel ranks, as Washington revealed it is mulling non-lethal aid to the insurgency.

Abdo Hussameddin announced his resignation in a video posted by activists on YouTube, saying he was joining the revolt.

Mitt Romney edged out rival Rick Santorum in a nail-biter vote in Ohio as he tightened his grip on the 2012 Republican presidential nomination with a string of Super Tuesday wins.

Santorum kept his hopes alive with a trio of victories in North Dakota, Oklahoma and Tennessee, but Romney took six states: Idaho, Massachusetts, Virginia, Vermont, Alaska and, after a torturous wait, Ohio.

U.S. President Barack Obama Tuesday described the violence in Syria as "heartbreaking," but cautioned there was no simple solution, warning unilateral military action would be a mistake.

"What's happening in Syria is heartbreaking, and outrageous, and what you've seen is the international community mobilize against the Assad regime," Obama told a White House press conference.

The United States will ensure Israel retains "military superiority" over its adversaries as the country faces the potential threat of a nuclear-armed Iran, Defense Secretary Leon Panetta said Tuesday.

"This is an ironclad pledge which says that the United States will provide whatever support is necessary so that Israel can maintain military superiority over any state or coalition of states, as well as non-state actors," Panetta told the top pro-Israel lobby in Washington, AIPAC.

Israel's Benjamin Netanyahu on Tuesday winds up a high-profile U.S. visit focused on Iran's perceived nuclear threat after warning that his country would not live in the "shadow of annihilation."

Netanyahu was to meet with U.S. Secretary of State Hillary Clinton and visit the U.S. Congress a day after keenly-watched talks with President Barack Obama against the backdrop of speculation over a possible Israeli strike on Iran.

Syrian state media on Tuesday lashed out at Washington for slapping sanctions on a key official broadcasting network, saying the U.S. move constituted a "violation" of press freedom.

Washington on Monday slapped economic sanctions on Syrian General Organization of Radio and TV, saying the state media network of Damascus was aiding the regime in its brutal campaign to put down a popular uprising.

A top U.S. official on Monday pledged to help Nigeria address security threats as Africa's most populous nation and largest oil producer deals with scores of attacks blamed on Islamist group Boko Haram.

"I think the United States wants to support Nigeria in every way that is appropriate from Nigeria's point of view, to deal with any threat here in this country," U.S. Under-Secretary for Political Affairs Wendy Sherman told reporters.