A US destroyer has arrived back in its home port after colliding with a container ship four times its size, leaving seven sailors missing.

World leaders and relatives of victims joined together around the globe today to pay tribute to the victims of the September 11 attacks with remembrance services including a tree-planting ceremony in Australia and the opening of a memorial garden in London.

Three US warships that left Japan to support the war against terrorism are returning to their home port near Tokyo.

Two more warships have set sail from a US base in Japan.