Richard Olson, US Special Representative for Pakistan and Afghanistan, told the Senate Foreign Relations Committee that the Barack Obama administration had conveyed to Pakistan that there could be no peace in the region until these cross-border attacks stopped, Dawn online reported.
Olson, who was the US Ambassador in Islamabad before taking up his current position, also emphasised the need for a constructive relationship between Kabul and Islamabad, which he said was essential for bringing peace and stability to the region.
According to Olson, relations between Pakistan and Afghanistan experienced a "significant improvement" when Afghan President Ashraf Ghani came to power but they "peaked and troughed" over the past year due to critical issues, including refugees, border management and counterterrorism.
He also underlined "some encouraging signs" of progress in recent months, adding that after a meeting in June between Afghan and Pakistani foreign policy chiefs, both sides agreed to coordinate at senior and tactical levels on border management issues.
"We support this mechanism and believe that more bilateral dialogue between Afghanistan and Pakistan will increase prospects for mutual understanding, regional peace and stability," Olson said.
In the wake of the deadly August 24 attack on the American University of Afghanistan, Kabul provided Islamabad with evidence that prompted the Pakistan military to conduct combing operations in a few key areas along the border. Pakistan is sharing the results of those operations with Afghanistan.
"Efforts to bring those behind the attack to justice are critical," said Olson, while noting that Pakistan's military operations in the Federally Administered Tribal Areas were also important.
He noted that the Pakistani military had made progress in shutting down terrorist safe havens through Operation Zarb-e-Azb and most recently in Operation Khyber III in the Rajgal Valley of Khyber Agency.
"While the progress Pakistan has made through its recent operations is laudable, its struggle with terrorism will not come to an end until it makes a decisive shift in its policy of tolerance towards externally-focused groups," Olson warned.
"US officials have been very clear with the most senior Pakistani leadership that Islamabad must target all militant groups without discrimination -- including those that target Pakistan's neighbours -- and close all safe havens."
The US diplomat told the committee that Pakistan's leaders had assured the US of their intention to do so.
Olson also said the US would also continue to support the India-Afghanistan relationship through the revival of a US-India-Afghanistan trilateral talks, which will take place next week on the margins of the UN General Assembly.
"We welcomed India's provision of training and non-lethal security assistance to Afghanistan and its significant development contributions over the past decade-plus," he said.
