BBC, Mar. 4: The US military has conducted an air strike against Taliban fighters in Afghanistan, just hours after President Donald Trump said he had a "very good talk" with a leader of the group.

The US signed a deal with the Taliban on Saturday aimed at bringing peace to Afghanistan after years of war.

But a US forces spokesman said it launched an air strike on Wednesday in response to Taliban fighters attacking Afghan forces in Helmand province.

The Taliban has not commented.

It was not immediately clear if there were any casualties.

What did the US say?

Wednesday's strike was the first by the US against the Taliban in 11 days, when a reduction in violence agreement began between the two sides in the lead-up to Saturday's pact.

In a statement on Twitter, Colonel Sonny Leggett, a spokesman for the US Forces in Afghanistan, said it was a "defensive strike" to disrupt an attack on an Afghan National Security Forces checkpoint.

The spokesman added that the US was still "committed to peace" but had a responsibility to defend its Afghan partners. He said Afghans and the US had complied with their side of the agreement, while the Taliban appeared intent on "squandering" the opportunity.

On Tuesday alone, he said the Taliban launched 43 attacks on checkpoints belonging to Afghan forces in Helmand.

"We call on the Taliban to stop needless attacks and uphold their commitments. As we have demonstrated, we will defend our partners when required," he wrote.

The Taliban has so far declined to confirm or deny responsibility for any of the attacks.

What's the background?

On Saturday the US and the Taliban signed an "agreement for bringing peace" to Afghanistan after more than 18 years of conflict.

The US and its Nato allies agreed to withdraw all troops within 14 months if the militants upheld the deal.

But violence surged in Afghanistan just days after the agreement was signed, with the Taliban ending a partial truce and resuming fighting with Afghan government troops.

Central to the obstacles facing the deal is a disagreement over prisoner swaps.

Under the accord, some 5,000 Taliban prisoners and 1,000 Afghan security force prisoners are meant to be exchanged by 10 March, when talks between the Taliban and the Afghan government are due to start.

But Afghanistan's President Ashraf Ghani said on Sunday his government had agreed to no such release. And on Monday the militants said talks would not take place if their prisoners were not released first.

Following reports of numerous Taliban attacks on Tuesday, Mr Trump shared a phone call with a leader of the group, Mullah Abdul Ghani Baradar, about keeping peace efforts on track.

The US president said it was a "very good talk", while the Taliban said Mr Trump had pledged to ask his Secretary of State Mike Pompeo to talk with Mr Ghani to make sure negotiations between the Afghan government and the Taliban went ahead as planned.

The Taliban have previously refused to negotiate with the Afghan government, so Saturday's deal was just with the US.

The US attacked Afghanistan in October 2001 to oust the Taliban, whom they said were harbouring Osama bin Laden and other al-Qaeda figures linked to the 9/11 attacks. The Taliban were removed from power but became an insurgent force that by 2018 was active in more than two-thirds of the country.