Somali pirates have attacked a US-flagged cargo ship off the coast of Somalia with rockets and automatic weapons, the ship's owner say.
The pirates on Tuesday failed to board the Liberty Sun and all crew of were unharmed, the Liberty Maritime Corporation (LMC) said.
"We are grateful and pleased that no one was injured and the crew and the ship are safe," the LMC statement said of the vessel which was carrying US food aid for African nations to Mombasa, Kenya.
The attack took place at about 11.30am local time (1530GMT), a US navy official said.
A US ship, the USS Bainbridge, responded to calls for assistance by the Liberty, but the pirates had left by the time it arrived about six hours later, Jack Hanzlik, a US navy captain, said.
It was the second assault in a week on a US-flagged ship in the region.
US snipers killed on Sunday three Somali pirates and freed the US ship captain they had been holding hostage for five days.
Moonlight offensive
Two cargo vessels were captured on Tuesday in the Gulf of Aden, taking at least 22 people hostage, a Nato spokesman said.
The hijackings of a Lebanese-owned freighter and a Greek merchant ship followed eight other hijackings by pirates in the busy shipping lanes of the Gulf of Aden and Indian Ocean - known as the Horn of Africa - since the beginning of April.
Armed men seized the first ship overnight - the Greek-owned MV Irene EM - and took the 22-man Filipino crew hostage.
Hours later the second vessel, the Togo-flagged MV Sea Horse, was taken about 140km off Somalia's coast.
Lieutenant-Commander Alexandre Fernandes, a Nato officer, said: "There was only three minutes between the [MV Irene's distress call] and the hijack.
"They attacked at night, which was very unusual. They were using the moonlight as it's still quite bright."
Root cause
Omar Abdirashid Ali Sharmarke, the Somali prime minister, told Al Jazeera: "We are actually trying to do our best to try and disrupt the activities before we go to the waters," he said.
"The root cause was always the lack of institutions to deal with dissidents.
"You cannot just contain pirates from the seaside, you have actually I think to dissolve the bases from the land. You have to prevent them before they go into the waters."
PHOTO CAPTION
A US Navy helicopter from the guided-missile cruiser USS Vella Gulf closes in on suspected pirates in the Gulf of Aden in February.
Al-Jazeera