ISLAMABAD (Reuters) - U.S. Senator John McCain said on Sunday there could be “no peace” in Afghanistan or the rest of the region without Pakistan’s cooperation, as he visited Islamabad ahead of a review from the United States of its Afghan war strategy.

FILE PHOTO: Sen. John McCain (R-AZ) asks a question as U.S. Defense Secretary James Mattis and Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford (unseen) testify before the Senate Armed Services Committee on Capitol Hill in Washington, D.C., U.S., June 13, 2017. REUTERS/Aaron P. Bernstein

McCain, chairman of the Senate Armed Services Committee, met Sartaj Aziz, Pakistan’s top foreign policy official, and also met army chief General Qamar Javed Bajwa.

“Our relationship is more important perhaps than ever before,” McCain told Pakistan TV as he left the meeting.

U.S. President Donald Trump’s administration is exploring hardening its approach toward Islamabad over Pakistan-based militants launching attacks in Afghanistan, two U.S. officials told Reuters last month.

“We will not have peace in the region without Pakistan,” McCain, who was accompanied by senators Lindsey Graham, Elizabeth Warren, Sheldon Whitehouse and David Perdue, said later.

Aziz, who is Special Adviser to the Prime Minister on Foreign Affairs because PM Nawaz Sharif holds the Foreign Ministry portfolio himself, said that the strategic partnership between Pakistan and the United States was “was critical to achieve peace and stability in the region and beyond”.

U.S. officials say they seek greater cooperation with Pakistan, not a rupture in ties, after the review the 16-year-old war in Afghanistan, due in mid-July, where some 8,800 U.S. troops remain to support the Western-backed government.

Experts on America’s longest war say militant safe havens in Pakistan have allowed Taliban-linked insurgents a place to plot attacks in Afghanistan and regroup after ground offensives. Critics say Islamabad is not doing enough to crack down on militants such as the Taliban-affiliated Haqqani network.

Pakistan argues that it has done a great deal to help the U.S. in tracking down terrorists and points out that it has suffered hundreds of deaths in Islamist militants attacks in response to its crackdowns.

Pakistan last week also reacted sharply when the U.S. State Department on June 26 designated as a terrorist Syed Salahuddin, leader of the largest Kashmiri militant group fighting against Indian rule, accusing the U.S. of acquiescing to the wishes of visiting Indian Prime Minister Narendra Modi.

Kashmir, ruled in part by India and Pakistan and claimed in entirety by both, is a hot-button issue between the nuclear-armed neighbors, which have fought two of their three wars since independence from Britain over the territory.

Aziz made a point on Sunday of mentioning what the foreign ministry called “gross human rights violations by the Indian security forces in Kashmir” and the international community’s “silence”.

Security forces in Indian-administered Kashmir have been accused by activists and rights groups of killing up to 100 separatist protesters since new mass anti-India demonstrations broke out in September. India argues its actions are justified.