A US team of military and intelligence experts has arrived in Nigeria to help with the search for 276 schoolgirls abducted by Islamist militants.
US Secretary of State John Kerry said "Our inter-agency team is hitting the ground in Nigeria now and they are going to be working in concert with President Goodluck Jonathan's government to do everything we can to return these girls to their families and their communities".
"We are also going to do everything possible to counter the menace of Boko Haram".
The group includes experts in intelligence, law enforcement and hostage negotiations, but fewer than 10 military troops are among them.
Washington is also considering a request to provide surveillance aircraft and intelligence, a senior US official told the Reuters news agency.
Michelle Obama shows her support
The US team arrived as a parent of one of the schoolgirls pleaded with countries from around the world to send more help. Boko Haram took the girls from a boarding school in the village of Chibok in the northern state of Borno more than three weeks ago.
But Shettima Haruma, whose daughter is among those taken, told Sky News he was "angry" with the Nigerian government's response.
"We are needing the government to take American people to come and help us" he said.
"Yes, we beg them. We beg Nigerians, those in another country like America, or London - now it's three weeks, nearly one month we didn't see any improvement, didn't see any letters from our daughters".
"We are afraid and we ask the other countries to come and help us".
The leader of Boko Haram, Abubakar Shekau, has threatened to sell the girls "on the market" and some of the group have already reportedly been trafficked to neighbouring Chad and Cameroon.
A further 11 girls, aged 12 to 15, have also been abducted from the northeastern village of Warabe.
The search for the missing schoolgirls is focused around the huge Sambisa Forest - the "hideout" of Boko Haram, whose name is said to figuratively mean "Western education is forbidden".
The UK, France and China have also pledged their support to the hunt.
Malala Yousafzai with the hashtag #BringBackOurGirls
Britain is sending a small team of advisers - possibly including some military officers - to help with planning and coordination. However, they will not take part in operations on the ground.
Mr. Jonathan said the abduction would be the "beginning of the end of terror" in the country.
Addressing the World Economic Forum in the capital, Abuja, he thanked the international community for its support and said "by God's grace we will conquer the terrorists".
Hillary Clinton has shown her support also
A social media campaign backed by a number of celebrities has sought to raise awareness of the girls' plight. The Twitter hashtag #BringBackOurGirls has been promoted by the likes of US First Lady Michelle Obama.
Actress Angelina Jolie has blamed a "culture of impunity" for the kidnapping.
"These men thought that they can get away with this, that they could abuse them in such a way, sell them, rape them, take them as property, because so many people have gotten away with this in the past because of this culture of impunity" she said.
