4 Americans killed during NATO training exercise

• The four Americans were Marines and were the only ones on board, according to local police.

Background: No cause for the crash has been provided, but there had been bad weather in the area and conditions were "difficult," AP writes.

• "It was a real storm. ... There was one meter of visibility, snow and storm in the mountains, ” Red Cross team leader Oerjan Kristensen told VG, a Norwegian newspaper.
• Kristensen estimated that winds were traveling at 30-40 meters per second — or over 70 miles per hour.
• “When it blows like that, it is difficult to stand upright,” Kristensen added.

Details: The weather also prevented crash site investigators and rescue operations from arriving at the scene, according to officials.

• “The weather is very bad in the area to complete work at the scene, but police will take it up again as soon as the weather conditions allow it,” operations manager Ivar Bo Nilsson from the Norland police district said.

• Kristensen said that the risk of landslides and the remoteness of the crash site were also in the way of rescue operations.

The big picture: About 30,000 troops from NATO countries are training in Norway in drills that the defensive alliance planned this month. The drills are scheduled to run until April.

• Norway hosts the “long-planned and regular” training every two years, per the Washington Post.