TOKYO (AP) _ Being charged with the safety of a ship carrying 1.7 tons of lethal plutonium halfway around the globe is enough to make anybody nervous, and Yoshiaki Hosono is relieved his mission is over.

Hosono, 56, commands the Shikishima, an armed Japanese coast guard ship that escorted a freighter carrying the plutonium on a two-month trip from France. The journey ended Tuesday as the Akatsuki Maru pulled into Tokai, a port north of Tokyo, with the cargo.

''There was always tension,'' he told reporters Thursday.

''For example, an overhead plane that you can't immediately identify doesn't necessarily contain terrorists, but it's like anything else you don't know about - it makes you nervous.''

The shipment met with widespread criticism because of worries about possible terrorist attacks or environmental damage that might have resulted from an accident. Hundreds of demonstrators protested the ship's arrival Tuesday, and several nations demanded that the ship stay out of their waters.

Plutonium is one of the world's most deadly substances, and a small speck can cause cancer if inhaled.

The voyage is part of a plan to bring more than 30 tons of plutonium from reprocessing plants in France for use in fast-breeder reactors, which would produce more plutonium than they consume.

But in an apparent response to international criticism, officials said in December that Japan is reconsidering its nuclear power plans.

Hosono gave what appeared to be the first official account of the ship's route around Africa and Australia which, despite government efforts to keep it secret, was revealed by the environmental group Greenpeace.