ISLAMABAD, Pakistan (CNN) - U.S. Homeland Security Secretary Janet Napolitano, on a visit to Pakistan, discussed with Pakistani leaders the fight against terrorism, as well as how the two countries share information, she said Friday.
"The key concept is, you just can't start protecting the homeland at the borders of the United States," she said.
Napolitano has met with President Asif Ali Zardari and was to meet with the country's prime minister and interior minister.
Napolitano said U.S. officials were working on several issues with Pakistani officials, including ways to monitor who is traveling from Pakistan to the United States, as well as the protection of Pakistan's own borders.
A key part of Pakistan's border protection, she said, involves stopping the drug trafficking that comes in through Pakistanand "ultimately makes its way into the United States."
U.S. officials are using some of the techniques and expertise developed in the United States to help Pakistan, she said.