Two three-month-old female white Bengal tiger cubs play with a zoo keeper in their enclosure at the Buenos Aires' Zoo, in Argentina, on April 17, 2014. Captive white Bengal tiger Cloe, gave birth to three cubs – two females and one male – on January 14, 2014. (Photo by Juan Mabromata/AFP Photo)

In the spring of 1965, within weeks of 3,500 American Marines arriving in Vietnam, a 39-year-old Briton named Larry Burrows began work on a feature for LIFE magazine, chronicling the day-to-day experience of U.S. troops on the ground – and in the air – in the midst of the rapidly widening war. The photographs in this gallery focus on a calamitous March 31, 1965, helicopter mission; Burrows’ “report from Da Nang”, featuring his pictures and his personal account of the harrowing operation, was published two weeks later as a now-famous cover story in the April 16, 1965, issue of LIFE.

Photo: Man your battle stations: The crew chief of helicopter Yankee Papa 13, lance corporal James C. Farley, mans an M-60 machine gun during a mission near Da Nang, Vietnam on March 31, 1965. (Photo by Larry Burrows/Time & Life Pictures)

In this photograph taken on April 16, 2014, a veterinary staff member of the Sumatran Orangutan Conservation Programme center conducts medical examinations on a 14-year-old male orangutan found with air gun metal pellets embedded in his body in Sibolangit district in northern Sumatra island. (Photo by Sutanta Aditya/AFP Photo)

“The most serious health problem in the U.S. today is obesity.” Sounds familiar, doesn’t it? But that pronouncement about obesity’s primacy in the hierarchy of national health problems is not new. Rather, it’s the opening line to a remarkable article published 60 years ago in LIFE magazine. This photographs made by Martha Holmes to illustrate that March 1954 article, titled “The Plague of Overweight.” Photo: Dorothy Bradley (left), photographed for LIFE magazine article on obesity, 1949. (Photo by Martha Holmes/Time & Life Pictures)

Tim Laman is a field biologist and wildlife photojournalist. His pioneering research in the rain forest canopy in Borneo led to a PhD from Harvard and his first National Geographic article in 1997. Since then, he has pursued his passion for exploring wild places and documenting little-known and endangered wildlife by becoming a regular contributor to National Geographic. He has eighteen articles to his credit to date, all of which have had a conservation message. Some have focused on endangered species such as Orangutans or Hornbills, while others, such as a series of articles on Conservation International’s Biodiversity Hotspots, have highlighted regions under intense pressure.

A new species of monkey found in the Democratic Republic of the Congo and identified as Lesula (Cercopithecus lomamiensis) is seen in this undated photograph from an article published September 12, 2012 in the science journal PLOS One. The monkey was first seen in 2007 by researchers John and Terese Hart of the Peabody Museum of Natural History at Yale Research Project. The finding of C. lomamiensis represents only the second new species of African monkey to be discovered in the past 28 years, according to the research article. (Photo by Hart J. A., Detwiler K. M., Gilbert C. C./Reuters)

A member of staff prepares herself a crisp sandwich in the Simply Crispy sandwich cafe in Belfast, northern Ireland January 12, 2015. The sandwich shop which opened on Monday is the world's first crisp sandwich cafe, local media reported. The idea of a crisp sandwich cafe started as a joke article on a website called Ulster Fry. The hilarious piece poked fun at recent ridiculous foody trends like the cereal café that opened in London last year. What was once a satirical joke has now become reality, after Belfast cafe owner Andrew McMenamin decided to make it happen. Customers will be able to choose their bread and crisps and add cheese or ham to their sandwich, which will be served with soup and chips. (Photo by Cathal McNaughton/Reuters)

An E.T. doll is seen while construction workers prepare to dig into a landfill in Alamogordo, N.M., Saturday, April 26, 2014. Producers of a documentary are digging in the landfill in search of millions of cartridges of the Atari “E.T. The Extra-Terrestrial” game that has been called the worst game in the history of videogaming. A New York Times article from 1983 reported that Atari cartridges of “E.T. The Extraterrestrial” were dumped in the landfill in Alamogordo. (Photo by Juan Carlos Llorca/AP Photo)