NAIROBI, Kenya — The United Nations High Commission for Refugees has three months to close a refugee camp in eastern Kenya and send the more than 400,000 Somalis living there back to their country or else the Kenyan government will relocate them, Kenya’s Deputy President William Ruto has said.

The Kenyan government says the Dadaab refugee camp in eastern Kenya has become a recruitment center for the extremist group al-Shabab whose gunmen last week killed 148 people at the country’s Garissa College University. Ruto said in a rally on Saturday that Kenya must be secured at all costs.

“We have asked the UNHCR to relocate the refugees in three months, failure to which we shall relocate them ourselves. The way America changed after 9/11 is the way Kenya will change after Garissa,” Ruto said in a statement distributed by his press office.

Kenyan President Uhuru Kenyatta vowed a sharp response to last week’s attack at the university. Kenyan warplanes attacked suspected militant positions in Somalia, and the government said Wednesday that it was freezing accounts of organizations and individuals suspected of financing Islamic extremists.

Al-Shabab militants have vowed retribution on Kenya for deploying troops to Somalia in October 2011 to fight the militant group blamed for cross-border attacks.

The April 2 Garissa University College attack is one of the worst attacks extremists have carried out in the country, second only to the 1998 bombing of the U.S. embassy in Nairobi.

The opposition has called for the withdrawal of Kenyan troops from Somalia, a call that the government has dismissed.