The US Secretary of Defence Leon Panetta visited the head of the National Directorate of Security, Asadullah Khalid, at a US hospital on Saturday.
"Panetta expressed satisfaction about Mr. Khalid's rapidly improving health," the Afghan ministry of foreign affairs said in a statement, adding that "both sides also discussed the security situation in the country, the Afghanistan-US Bilateral Security Agreement and reconciliation efforts."
Asadullah Khalid, who survived a suicide attack at a National Directorate of Security guesthouse in Kabul on December 6, incurred serious injuries to the lower part of his body.
He was taken to the United States for treatment on December 15.
President Karzai has said that the attack on Mr Khalid was plotted in Quetta, where the Taliban's leadership is believed to be based. Pakistan rejected President Karzai's claim.
On December 22, President Barack Obama also visited Khalid in hospital.
Panetta's visit comes as President Karzai is flying to Washington to meet President Obama and discuss the bilateral security agreement and other seucrity-related issues.
President Karzai will also visit Asadullah Khalid.