UNITED STATES: The US was the world’s first country to develop the nuclear bomb, in the early 1940s, and is the only country to ever use it offensively, during World War II. The US has 2,700 deployed nukes, plus another 2,500 to 3,500 nukes on reserve, according to the International Commission on Nuclear Non-proliferation and Disarmament. The US is a signatory to the Nuclear Non-Proliferation Treaty. Here, the US Navy fires a Trident II, D-5 missile from the USS Tennessee, a submarine in the Atlantic Ocean off the coast of Florida in December 1989. Phil Sandlin/AP/FILE
RUSSIA: Russia first tested a nuclear bomb in 1949, and currently has 4,800 to 5,800 deployed nuclear bombs, plus another 8,150 on reserve. It is one of five nuclear-armed signatories to the Nuclear Non-Proliferation Treaty. The first Soviet atomic bomb RDS-1 (or Joe One) and the first Soviet hydrogen bomb RDS-6 (second from below) are on display at the Museum of the Russian Federal Nuclear Center 'All-Russian Scientific and Research Institute of Experimental Physics' in the Town of Sarov. Nikolai Moshkov/ITAR-TASS/Newscom/File
FRANCE: France first tested a nuclear weapon in 1960, and now has 300 deployed nukes. It is a signatory to the Nuclear Non-Proliferation Treaty. Seen here, French officers view a French nuclear test carried out in Reggane, in the southern Sahara desert in 1960. Reggane was the site where the first French nuclear bomb was tested on Feb. 13, 1960 before Algerian independence. AFP/Newscom/FILE
UNITED KINGDOM: Britain first tested a nuclear bomb (called 'Hurricane') in 1952. It currently has 160 deployed nukes. It is a signatory to the Nuclear Non-Proliferation Treaty. Sailors are seen aboard the HMS Vanguard in Holy Lach, Scotland, in 1992. Nuclear-armed submarines from Britain and France collided deep under the Atlantic Ocean in February 2009, causing damage to both vessels but releasing no radioactivity, a British official said. The HMS Vanguard, Britain's first Trident class nuclear-armed submarine, and the French Le Triomphant submarine, which was also carrying nuclear missiles, both suffered minor damage. Chris Bacon/AP/FILE
CHINA: Beijing became a nuclear power in 1964. It currently is estimated to have 130-186 deployed nukes, plus another 54 on reserve. It is a signatory to the Nuclear Non-Proliferation Treaty. Chinese construction workers are seen here walking past a picture of a Chinese missile during renovations in Beijing's Military History Museum in May 1999. Natalie Behring/Reuters/FILE
ISRAEL: Israel refuses to confirm or deny it has nuclear weapons, but it is widely believed to have between 60 and 200 deployed nukes. Israel has declined to sign the Nuclear Non Proliferation Treaty, and is one of four nuclear-armed countries that the NPT does not recognize as a nuclear weapons state. Here, US President Barack Obama greets Israel's Deputy Prime Minister and Minister of Intelligence and Atomic Energy Dan Meridor at the Nuclear Security Summit in Washington on April 12. Kevin Lamarque/Reuters
INDIA: In 1974, India first tested a nuclear bomb, called 'smiling Buddha.' India now has 60 to 70 deployed nukes. It has not signed the Nuclear Non Proliferation Treaty. Here, Indian students take part in a peace rally in Mumbai in August 2008, to mourn victims of the atomic bombing of Hiroshima in 1945 as peace rallies and memorial services the world over marked the world's first nuclear attack on Hiroshima, Japan. Sajjad Hussain/AFP/Getty Images/Newscom/FILE
PAKISTAN: Pakistan is believed to have been developing nuclear weapons since the 1970s, though it did not test a nuclear weapon until 1998. Pakistan now has 60 deployed nukes. Pakistani Prime Minister Zulfiqar Ali Bhutto promised in 1974 that if India built nuclear weapons Pakistan would too, 'even if we have to eat grass.' It has not signed the Nuclear Non Proliferation Treaty. A Pakistani missile test is seen here on May 8 at an undisclosed location. The two ballistic missiles tested are capable of carrying nuclear warheads, the Pakistani military said. Pakistan's Inter Services Public Relations/AP
NORTH KOREA: North Korea pulled out of the Nuclear Non Proliferation Treaty in 2003 and subsequently developed and tested a nuclear bomb, in 2006. It is estimated to have enough plutonium to make five or six nuclear bombs, according to the International Commission on Nuclear Non-proliferation and Disarmament. Here, a satellite image from DigitalGlobe taken in January 2006 shows Yongbyon nuclear reactor in North Korea. North Korea had said it shut Yongbyon, the nuclear reactor that provides the state with material to make weapons-grade plutonium, China's Xinhua news agency quoted a North Korean official as saying in July 2007. DigitalGloble/Reuters/FILE
The new revelation underlines questions about how thoroughly the aviation industry and government regulators screen pilots for psychological problems.
ByDavid McHugh & Joan Lowy, Associated Press
Lufthansa knew that the co-pilot of the passenger plane that crashed in the French Alps last week had suffered from an episode of "severe depression" before he finished his flight training with the German airline.