Trump says US in 'very strong' negotiations in Afghanistan

US President Donald Trump said on Thursday the United States was "in very strong" peace negotiations in Afghanistan but he did not known whether they would be successful.

"I really think the people of Afghanistan ... are tired of fighting," Trump told reporters after delivering a Thanksgiving holiday message to US troops in Afghanistan, scene of one of America's longest-ever wars.

"We are talking about peace and we'll see if that happens ... We have negotiations going on. I don't know that they are going to be successful, probably they're not. Who knows? They might be, they might not be."

Trump was speaking after Taliban leaders met with US special envoy Zalmay Khalilzad at their political headquarters in Qatar last week for the second time in the past month.

Khalilzad said on Sunday he hoped to reach a peace deal by April 20, a deadline that coincides with the date set for presidential elections in Afghanistan.

However, the Taliban said their three-day meeting with Khalilzad to pave the way for peace talks ended with no agreement on any issue and they had not accepted any deadline set by the United States to wrap up talks.

Khalilzad's public statement that the Taliban believe they will "not win militarily" apparently angered senior members of the group, who warned US officials against mixed messages that could muddle the peace process.

US troops invaded Afghanistan in 2001 as part of a campaign to topple the Taliban following the Sept. 11 attacks in the United States. Some 14,000 US personnel are still there.

The Taliban have strengthened their grip over the past three years, with the government in Kabul controlling just 56 per cent of Afghanistan, down from 72 per cent in 2015, a US government report showed this month.

Two senior US officials confirmed this week that a second round of peace talks ended last week and the Taliban expected Khalilzad to visit Qatar for a meeting before the end of 2018.

Trump hinted he may go to Afghanistan, a country he has yet to visit almost two years into his presidency, even though previous US commanders-in-chief have routinely visited troops in active war zones.

Trump told troops in the teleconference that while they were fighting, he was taking tough action to secure the southern borders of the United States from illegal immigration.

"You are doing it over there; we are doing it over here," he said.

"We have a very powerful border now ... We took old broken wall and we wrapped it with barbed wire plus ... nobody is getting through these walls and we're going to make sure they're the right people because that's what you and your family want," he said.

"That's why we're all fighting – you know, we're fighting for borders, we're fighting for our country."