US

US First Lady Michelle Obama (C) and Peng Liyuan, wife of Chinese President Xi Jinping are escorted by officials as they visit the Forbidden City in Beijing on March 21, 2014.  Michelle Obama arrived in Beijing with her mother and daughters to kick off a seven-day, three-city tour where she will focus on education and cultural exchange.

Andy Wong/AFP

US first lady Michelle Obama and Peng Liyuan, wife of Chinese president Xi Jinping, are escorted by officials as they visit the Forbidden City in Beijing on Friday. Mrs Obama arrived in Beijing with her mother and daughters to kick off a seven-day, three-city tour where she will focus on education and cultural exchange.

A Filipino student shouts anti-US slogans outside the US embassy in Manila, Philippines, 21 March 2014 in a rally condemning the docking of the USS Blue Ridge and the upcoming visit of US President Barack Obama to the country. Activists also called for an end to the presence of US troops in the country and the Visiting Forces Agreement (VFA). Obama is to visit Japan, South Korea, Malaysia and the Philippines in late April. The trip is part of his efforts to broaden US engagement in the Asia-Pacific region on all fronts, from strategic security issues to trade and diplomacy. Obama had originally planned an Asia trip for late 2013, but was forced to cancel during the budget and debt limit crisis that closed the US government for more than two weeks in October.

Dennis M. Sabangan/EPA

A Filipino student protests outside the US embassy in Manila, Philippines, in a rally condemning the docking of the USS Blue Ridge and the upcoming visit of US President Barack Obama. Activists also called for an end to the presence of US troops in the country and the Visiting Forces Agreement.

Heavy smoke pours from the debris as the Fire Department of New York (FDNY) responds to a 5-alarm fire and building collapse at 1646 Park Ave in the Harlem neighborhood of Manhattan March 12, 2014 in New York City. Reports of an explosion were heard before the collapse of two multiple-dwelling buildings that left at least 11 injured.

Andrew Burton/Getty Images

Heavy smoke pours from the debris as the New York fire department responds to a 5-alarm fire and building collapse at 1646 Park Avenue in the Harlem area of Manhattan in New York City. Reports of an explosion were heard before the collapse of two multiple-dwelling buildings that left at least 11 injured

Firemen spray their water cannon at protesters who are forcing their way closer to U.S. Embassy in Manila, Philippines, Tuesday, Feb. 25, 2014 during a protest against the forthcoming visit of U.S. President Barack Obama. The protesters were also calling for the pullout of U.S. troops in the country under the Visiting Forces Agreement

Bullit Marquez/AP

Firemen spray a water cannon at protesters forcing their way towards the US embassy in Manila on Tuesday during a protest against the forthcoming visit of US president Barack Obama. The protesters were also calling for the pullout of US troops in the country under the Visiting Forces Agreement.

A troop of the Japan Ground Self-Defense Force participates with the US Marine Corps of  Expeditionary Fire Support System during the US -JAPAN military exercise Iron Fist 2014  outside the USMC base in Pendleton, California on February 06, 2014.

Joe Klamar/AFP

A member of the Japan Ground Self-Defence Force takes part in the US -Japan Exercise Iron Fist manoeuvres at the US Marine base in Pendleton, California

TOPSHOTS Ukrainian pro-EU protesters kee...TOPSHOTS Ukrainian pro-EU protesters keep warm around a bonfire in Independence Square in Kiev early on January 17, 2014. The European Union and the United States expressed concern after the Ukrainian parliament passed laws to curb the right to protest, a move the opposition called a power grab.  Western rights groups meanwhile denounced the bills as an attempt by President Viktor Yanukovych to impose a "dictatorship" and called on him to veto the legislation. AFP PHOTO/GENYA SAVILOVGENYA SAVILOV/AFP/Getty Images

Genya Savilov/AFP

Pro-EU protesters keep warm round a bonfire in Independence Square, Kiev, Ukraine. The EU and US expressed concern after the Ukrainian parliament passed laws to curb the right to protest, a move the opposition described as a power grab. Western rights groups denounced the bills as an attempt by President Viktor Yanukovych to impose a ‘dictatorship’ and called on him to veto the legislation. Read more

A man walks past a car partially covered in ice in Baltimore where temperatures continue to remain well below freezing.

Patrick Semansky/AP

North America has been hit by the coldest temperatures in decades after a a polar vortex led to extreme weather conditions. In Baltimore, temperatures remain well below freezing, with ice forming on buildings, cars and roads.

Ice forms on an abandoned dock structure in the East River due to unusually low temperatures caused by a Polar Vortex in New York January 7, 2014.

Lucas Jackson/Reuters

Ice forms on an abandoned dock in the East River as extreme freezing conditions, known as a polar vortex, hit New York. The Atlantic seaboard of the US is gripped by the coldest weather it has had in decades

National Park Service workers spread salt on icy steps of the Lincoln Memorial in Washington...National Park Service workers spread salt on the icy steps of the Lincoln Memorial in Washington January 3, 2014. A heavy snowstorm and dangerously cold conditions gripped the northeastern United States on Friday, delaying flights, paralyzing road travel and closing schools and government offices across the region.  REUTERS/Gary Cameron

Gary Cameron /Reuters

National Park Service workers spread salt on the icy steps of the Lincoln Memorial in Washington. A heavy snowstorm and dangerously cold conditions gripped the northeastern United States on Friday. Read more

Former US presidents Bill Clinton (L), George W. Bush (C) and Clinton's daughter Chelsea Clinton (R) attend the official memorial ceremony for late South African president Nelson Mandela at FNB Stadium in Johannesburg, South Africa, 10 December 2013. Nobel Peace Prize winner Nelson Mandela died on 05 December at the age of 95.

Dai Kurokawa/EPA

Former US presidents Bill Clinton, George W. Bush and Mr Clinton’s daughter Chelsea Clinton attend the official memorial ceremony for Nelson Mandela