Timeline: All you need to know about Afghanistan crisis

Afghanistan: Taliban insurgents started entering Kabul on Sunday after gaining control of all major cities in Afghanistan except the capital. Here are some of the key events in the progress of the Islamic militant advance in recent months. Other lethal attacks have taken place, some accused on the Taliban and some on separate jihadist organisations, including an offshoot of Islamic State.

Communications between the Taliban and the Afghan government over a political compromise that could guide to a peace pact, supported by the United States and its allies, have not produced a significant step.

April 14 - President Joe Biden declares that US troops will withdraw from Afghanistan from May 1 to September 11, ending America's most lasting war. It was an expansion of the previous withdrawal period of May 1 agreed between the United States and the Taliban.

May 4 - Taliban soldiers originate a major offensive against Afghan troops in the southern Helmand region. They also charge in at least six other territories.

May 11 - The Taliban conquer the Nerkh district just outside the capital, Kabul, as violence escalates in the country.

June 7 - Senior government executives say more than 150 Afghan officers are killed within 24 hours as the fighting escalates. They add that fighting is raging in 26 of the country's 34 regions.

June 22 - Taliban fighters carry out a line of attacks in the country's north, far from their traditional citadels in the south. The UN envoy to Afghanistan says they have occupied more than 50 of 370 districts.

July 2 - US troops calmly withdraw from their central military base in Afghanistan - Bagram Air Base, an hour's journey from Kabul. This dramatically ended American association in the war.

July 5 - The Taliban state they can submit a written peace proposal to the Afghan government as soon as possible.

July 21 - Taliban insurgents control about half of the country's districts, according to the senior US general, emphasizing the scale and speed of their march.

July 25 - The United States promises to continue "in the coming weeks" to support Afghan troops with increased airstrikes to assist them in countering Taliban attacks.

July 26 - The United Nations declares nearly 2,400 Afghan civilians were executed or injured in escalating violence in May and June, the highest number since the months since records began in 2009.

August 6 - Zaranj in the south of the country becomes the first provincial capital to fall to the Taliban for years. Much more follows in the ensuing days, including the esteemed city of Kunduz in the north.

August 13 - Four more provincial capitals fall in a day, including Kandahar, the country's second city and the Taliban's spiritual home. Another important city, Herat, is overrun in the west, and the veteran commander Mohammad Ismail Khan, one of the preeminent fighters facing the Taliban, is arrested.

-14 August-The Taliban take the large northern city of Mazar-i-Sharif, and with little resistance Pul-e-Alam, capital of Logar area, just 70 km south of Kabul. The United States is sending more troops to evacuate its citizens from Kabul as Afghan President Ashraf Ghani says he is consulting with local and international partners on the next steps.

August 15 - The Taliban take the main eastern city of Jalalabad without a fight and effectively surround Kabul.

August 15 - Taliban insurgents enter Kabul, says an Interior Ministry official, while the United States evacuates diplomats by helicopter from its embassy.