The Navy’s Pacific-based Seventh Fleet announced on its Facebook page that the aircraft carrier in position, the U.S.S. Ronald Reagan, had been moved slightly away from the Fukushima Daiichi plant after finding “low level” radioactive contamination “in the air and on its aircraft operating in the area.” But the Navy said that operations to provide disaster relief had already resumed north of Sendai.

Most important to those relief efforts: helicopters. As depicted in the video above, released by the Navy on Sunday, Navy helicopters like the Reagan’s SH-60 Seahawks are delivering “water, blankets and food” and scouring the stricken areas for survivors. Ten operations already launched today, despite the repositioning.

And it was the copter crews that flew into the “low level” radiation areas. According to the New York Times, the helicopters were 60 miles from the plant, “suggesting widening environmental contamination.”

The contamination may be spreading. But so is the Navy’s assistance role in the relief effort. Seventh Fleet said it expects the U.S.S. Tortuga to arrive on Tuesday at the eastern coast of Hokkaido, carrying two heavy-lift MH-53 helicopters. It’ll pick up Japanese troops and vehicles and send them on to Aomori, in northern Honshu. Four more ships are expected to arrive starting on Wednesday: the Blue Ridge, the Essex, the Harpers Ferry and the Germantown.

Retired Capt. Jan van Tol, who commanded the Essex during the 2005 tsunami relief missions in Indonesia, explained that heavy-lift helicopters are needed “given the likely damage to coastal transportation infrastructure and the rugged Japanese terrain.” He told Politico, “Essex is on her way up from Malaysia (means a week away…), and other big decks will no doubt be assigned. They’re the real assets for this given their heavy helo lift capacity, though the carriers will no doubt get the headlines with their SH-60s. (Remember that operating the heavy helos is not merely a matter of the deck space (of which the CVNs obviously have a lot more), but also of the aircraft maintenance capability needed to keep the helos operating (and I expect they’ll be worked very heavily).”

The enormous human and environmental damage of Friday’s quake and tsunami have yet to be fully tallied. But as of Monday, the Japan Meteorological Agency registered at least three aftershocks “larger than magnitude 7.0” and some 44 aftershocks greater than 6.0.