NAIROBI, Kenya — Kenya's president asked the United States on Tuesday to lead a greater international effort to stabilize neighboring Somalia, while visiting U.S. Vice President Joe Biden said the U.S. is committed to helping Kenya see regional stability.

The request that the U.S. do more to combat rising militancy in Somalia comes three days after the arrests of two New Jersey men attempting to fly there. The two are charged with conspiring to kill, maim and kidnap persons outside the U.S. by joining al-Shabab, a Somali militant group designated by the U.S. in 2008 as a terrorist organization.

Kenyan President Mwai Kibaki said Somalia is a high priority for both the U.S. and Kenya. The country hasn't had an effective central government in 19 years, a situation that has allowed militancy and piracy to flourish.

"This matter must be addressed with greater urgency. We have asked the U.S. government to provide leadership to forge a concerted international effort to stabilize Somalia," Kibaki said.

Biden said the U.S. recognizes that Kenya's long-term stability and development is tied to regional stability.

"I assured the president and the prime minister the United States supports Kenya's efforts to secure the border in the face of very real threats from those who wish to spread chaos through despair and violence," Biden said during a joint news conference at Kibaki's Nairobi residence.

Biden is in the East African nation, the birthplace of President Barack Obama's father, to press for political reforms in the country and discuss the situation in Somalia and Sudan.

If Kenya strengthens its rule of law, the country will open the door to greater U.S. aid and investment, Biden said, encouraging Kenya to continue with reforms initiated after the country's postelection violence. More than 1,000 people were killed after the December 2007 poll.

"Americans want to do business here, they want to travel here, and with the right climate, they will come," Biden said.

While her husband was at Nairobi's State House, Jill Biden, their daughter Ashley, 29, and granddaughter Maisy, 9, visited Kibera, the largest slum in the country.

There they heard testimonials from two women living with HIV and visited a girl who is part of a group of adolescents who have been trained with skills to enable them earn an income and cope with life in the rough slum.

The HIV-positive women and girls are beneficiaries of U.S.-funded organizations. Moving from one venue to another, Jill Biden trudged in ankle-high mud through a maze of alleyways. Her 20-minute walk brought business to a standstill.

The vice president and his wife later laid a wreath at a memorial for the 1998 bombing against the U.S. Embassy in Nairobi. That bombing and a simultaneous one against the U.S. Embassy in neighboring Tanzania killed 224 people.

On Wednesday, the vice president is scheduled to give what he said would be a major speech on Kenya. The Bidens are also scheduled to visit Nairobi National Park to view wildlife before traveling to South Africa for the opening of football's World Cup later in the week.

Biden began his three-African nation tour on Monday in Egypt where he met with that country's leader, Hosni Mubarak, and discussed how their two countries and other allies can find ways to address the humanitarian, economic, security and political situation in Gaza.

Associated Press writer Tom Odula in Nairobi, Kenya contributed to this report.