A US Senate delegation paid a rare visit today to a key tribal district along the Afghanistan border, an erstwhile stronghold of Taliban recently taken by the army, and expressed support for Pakistan's counterterrorism campaign. The four-member, bipartisan US Senate delegation, led by former presidential candidate John McCain, visited the restive North Waziristan tribal region, and later called on the Adviser to the Prime Minister on Foreign Affairs Sartaj Aziz, Pakistan foreign ministry said in a statement. "McCain and his colleagues deeply appreciated the enormous success achieved by Pakistan in its counterterrorism campaign," the statement said. Aziz reiterated Pakistan's efforts to keep the Pakistan-US partnership on track and thanked McCain for his positive comments regarding the importance of bilateral relation, it said. Earlier, McCain visited the North Waziristan tribal region, where army has launched a campaign in 2014 to flush out militants and destroy their bases in the remote mountainous region, straddling across the Afghanistan border. The region, an erstwhile stronghold of al-Qaida and Taliban, is largely banned for foreigners and visits by foreign delegations are rare. McCain also met country's powerful army chief General Raheel Sharif in an overnight meeting and discussed matters of mutual interest and regional security. The visit comes at a delicate time when relations between the two country are at a new low after US Congress in May blocked the subsidised sale of eight F-16 fighter jets to Pakistan, accusing it of not being serious enough in fight against terrorism.