US Secretary of State Mike Pompeo met Afghan President Ashraf Ghani during an unannounced visit to Kabul on Tuesday to discuss ongoing peace talks with the Taliban and the security situation ahead of Afghan presidential polls in September.

Pompeo stopped over on his way to New Delhi for meetings with Indian Prime Minister Narendra Modi and other officials.

His visit to Afghanistan, which lasted about seven hours, comes ahead of a seventh round of peace talks between Taliban leaders and US officials aimed at finding a political settlement to end the 18-year-old war in Afghanistan. The next round of peace talks is scheduled to begin on June 29 in Doha.

“I hope we have a peace deal before September 1. That's certainly our mission set,” Pompeo said.

The talks between the United States and the Taliban will focus on working out a timeline for the withdrawal of US-led troops from Afghanistan and on a Taliban guarantee that militants will not plot attacks from Afghan soil.

“While we've made clear to the Taliban that we are prepared to remove our forces, I want to be clear, we've not yet agreed on a timeline to do so,” said Pompeo.

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About 20,000 foreign troops, most of them American, are in Afghanistan as part of a US-led NATO mission to train, assist and advise Afghan forces. Some US forces carry out counter-terrorism operations.

In return for the withdrawal of foreign forces, the United States is demanding the Taliban guarantee that Afghanistan will not be used as a base for militant attacks.

“We agree that peace is our highest priority and that Afghanistan must never again serve as a platform for international terrorism.”

He said the two sides are nearly ready to conclude a draft text outlining the Taliban's commitment to join fellow Afghans in ensuring that Afghan soil never again becomes a safe haven for “terrorists”.

The hardline group now controls more Afghan territory than at any time since it was toppled from power by US-led forces in 2001.

At least 3,804 civilians were killed in the war last year, according to the United Nations. Thousands of Afghan soldiers, police and Taliban were also killed.

Taliban leaders nevertheless vowed this month to sustain the fight until their objectives were reached.

US-Taliban talks: As hopes rise of a deal, what comes next?

But momentum for talks with the Taliban is steadily building, with a special US peace envoy for Afghanistan, Zalmay Khalilzad, pushing the process and insurgent leaders showing serious interest in negotiating for the first time. Ghani has also offered repeatedly to talk with the Taliban but the group insists it will not deal directly with the Ghani government.

“All sides agree that finalizing a US-Taliban understanding on terrorism and foreign troop presence will open the door to intra-Afghan dialogue and negotiation,” Pompeo said, adding that next step is at the heart of the US effort.

“We are not and will not negotiate with the Taliban on behalf of the government or people of Afghanistan.”

Pompeo's meeting with Ghani came as members of the opposition party held a large public gathering in Kabul to protest against his overstaying in power after his five-year term ended in May.

Ghani has refused to step down and Afghanistans Supreme Court says he can stay in office until the delayed presidential election, now scheduled for September, in which he will seek a second term.

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Political opponents of Ghani met Pompeo and US officials.

Preparation for the polls and a crucial chance to end the war with the Taliban are running in parallel, with international diplomats and politicians based in Kabul trying to prevent them running into each other.

Many Afghans are concerned that US President Donald Trump's administration, in its haste to end the war, could push for concessions that might weaken the democratic gains of the post-Taliban era.