Key events in India-Pakistan relations since Partition

In this Feb. 20, 1999, file photo, Pakistani Prime Minister Nawaz Sharif, left, and his Indian counterpart Atal Bihari Vajpayee wave upon Vajpayee's a

In this September 1947, file photo hundreds of Muslim refugees crowd on top a train leaving New Delhi for Pakistan. After Britain ended its colonial r

In this Nov. 9, 1947, file photo, Indian Sikh troops take up roadside positions on the Baramula Road to help force invaders further away from the Kash

In this Sept. 6, 1965, file photo, Indian troops are on the move in Kashmir against guerrilla forces. India and Pakistan fought a second war over Kash

In this Dec. 7, 1971, file photo, Indian troops advance inside the Northwest sector of East Pakistan. In 1971 India Pakistan fought their third war in

In this June 28, 1972, file photo, Indian Prime Minister Indira Gandhi, right, and President of Pakistan Zulfikar Ali Bhutto shake hands after signing

In this Dec. 22, 1974, file photo, Indian Prime Minister Indira Gandhi, center, examines a piece of rock at the nuclear test site in Pokhran, southeas

In this May 12, 1998, file photo, a sampling of Indian newspaper headlines announces India's test of nuclear devices. In May 1998, India detonated fiv

n this May 30, 1999, file photo, Indian army soldiers fire artillery in the northernmost part of the Kargil region, located some 225 kilometers (140 m

In this July 15, 2001, file photo, Pakistani President Gen. Pervez Musharraf, left, begins talks with Indian Prime Minister Atal Bihari Vajpayee in Ag

In this Dec. 13, 2001, file photo, Indian Black Cat commandos escort civilians outside the Parliament House as half a dozen armed men stormed the comp

In this Feb.22, 2007, file photo, Pakistan bound Samjhauta Express, moves past the damaged coaches of Sunday's fire in Deewana, about 80 kilometers (5

In this Oct. 22, 2008, file photo, President of Pakistan-administered Kashmir, Raja Zulqarnain Khan waves after flagging off trucks to the Indian side

In this Nov. 29, 2008, file photo, an Indian soldier takes cover as the Taj Mahal hotel burns during gun battle between Indian military and militants

In this Nov. 21, 2012, file photo, an activist of India's main opposition Bharatiya Janata Party (BJP) holds a portrait of Mohammed Ajmal Kasab with a

In this May 26, 2014, file photo, India's Prime Minister Narendra Modi, left, prepares to shake hands with his Pakistani counterpart Nawaz Sharif, as

In this Dec. 25, 2015, file photo released by Press Information Department, India's Prime Minister Narendra Modi, center right, reviews an honor guard

In this Jan.5, 2016, file photo, an Indian military commando is seen on the top of a building at the Indian air force base during an attack by gunmen

In this July 9, 2016, file photo, Kashmiri villagers carry the body of Burhan Wani, chief of operations of Indian Kashmir's largest rebel group Hizbul

In this Sept. 18, 2016, file photo, Indian army soldiers arrive at the army base which was attacked by suspected rebels in the town of Uri, west of Sr

India and Pakistan have had testy relations at best since independence. Some key dates that helped define the South Asian nations:

August 1947 - Britain ends its colonial rule over the Indian subcontinent, which becomes two independent nations — Hindu-majority, but secularly governed India and the Islamic republic of Pakistan. The division, widely known as Partition, sparks massive rioting that kills up to 1 million, while another 15 million flee their homes in one of the world's largest human migrations.

October 1947 - The two young nations begin a war over control of Kashmir, a Muslim-majority kingdom ruled by a Hindu maharaja. A U.N.-brokered cease-fire ends the war in a year with Kashmir divided between them.

January 1949 - India and Pakistan agree to a U.N. Security Council resolution calling for a referendum in which Kashmiris would determine their future; the vote never takes place.

September 1960 - India and Pakistan sign a World Bank-brokered Indus Water Treaty governing three rivers. It is the only India-Pakistan treaty that has held.

August 1965 - A second war begins over Kashmir, ending a month later in another U.N.-mandated ceasefire.

December 1971 - A third war is fought, this time as India supports secessionists in East Pakistan. The war ends with the creation of Bangladesh.

July 1972 - The countries' prime ministers sign an accord for the return of tens of thousands of Pakistani prisoners of war.

May 1974 - India conducts a nuclear test, becoming the first nation to do so that's not a permanent U.N. Security Council member.

December 1989 - Armed resistance to Indian rule in Kashmir begins. India accuses Pakistan of giving weapons and training to the fighters. Pakistan says it offers only "moral and diplomatic" support.

May 1998 - India detonates five nuclear devices in tests. Pakistan detonates six. Both are slapped with international sanctions.

February 1999 - Indian Prime Minister Atal Bihari Vajpayee rides a bus to the Pakistani city of Lahore to meet with Pakistan counterpart, Nawaz Sharif, and sign a major peace accord.

May 1999 - Conflict erupts in Kargil as Pakistani forces and Kashmiri fighters occupy Himalayan peaks. India launches air and ground strikes. The U.S. brokers peace.

May 2001 - Vajpayee and Pakistan's President Pervez Musharraf meet in the Indian city of Agra, but reach no agreements.

October 2001 - Insurgents attack the legislature building in Indian-controlled Kashmir, killing 38 people.

December 2001 - Gunmen attack India's Parliament, killing 14. India blames militant groups Lashkar-e-Taiba and Jaish-e-Muhammad, and deploys troops to its western frontier with Pakistan. The standoff ends in October 2002 after international mediation.

January 2004 - Musharraf and Vajpayee hold talks, launching bilateral negotiations to settle outstanding issues.

February 2007 - A train service between India and Pakistan, the Samjhauta Express, is bombed in northern India, killing 68.

October 2008 - India and Pakistan open a trade route across divided Kashmir for the first time in six decades.

November 2008 - Gunmen attack Mumbai, killing 166 people. India blames a Pakistan-based militant group.

May 2014 - India's new Prime Minister Narendra Modi invites Pakistani counterpart Nawaz Sharif to New Delhi for his inauguration.

December 2015 - Modi makes a surprise visit to the Pakistani city of Lahore on Sharif's birthday and the wedding of his granddaughter.

January 2016 - Six gunmen attack an Indian air force base in the northern town of Pathankot, killing seven soldiers in a battle that lasted nearly four days.

July 2016 - Indian soldiers kill Kashmiri rebel leader Burhan Wani, sparking months of anti-India protests and deadly clashes in the region.

September 2016 - Suspected rebels sneak into an Indian army base in Kashmir and kill 18 soldiers. Four attackers are also killed.