The US military defended its air strikes against Taliban fighters last week after the insurgent group accused Washington of breaching their agreement and warned of consequences if such actions continued. The Taliban launched a major offensive in the southern province of Helmand in a bid to take the provincial capital of Lashkar Gah, prompting US air strikes in support of Afghan security forces that were being overrun. Rocket attacks from the Taliban and retaliatory strikes from US and Afghan aircraft during the week-long offensive forced more than 5,600 families to flee their homes, seeking refuge in Lashkar Gah and the Nad Ali and Marja districts. "American forces have violated the Doha agreement in various forms by carrying out excessive air strikes following the new developments in Helmand province," Taliban spokesman Qari Muhammad Yousef Ahmadi said on Sunday. The US-Taliban agreement, signed in Doha, says foreign forces will leave Afghanistan in exchange for security guarantees and a pledge from the insurgents to sit down with the Afghan government to find a peaceful settlement to decades of war. "Responsibility and consequences from continuation of such actions shall fall squarely on the shoulders of the American side," Mr Ahmadi said. Air and drone strikes were also carried out in other provinces, he said. On Sunday, Col Sonny Leggett, spokesman for the US forces, denied the strikes breached the agreement. "The entire world has witnessed the Taliban's offensive operations in Helmand – attacks which injured and displaced thousands of innocent Afghan civilians," Col Leggett tweeted. He also repeated a call for "all sides" to reduce violence. Talks between Taliban and Afghan government negotiators began last month in Doha, but the process has been slow, while violence continues. Diplomats and officials said this was sapping the trust required for the talks to succeed. After the Helmand fighting, US special envoy to Afghanistan Zalmay Khalilzad said on Thursday that the Taliban agreed to reset their commitments and reduce the number of casualties. This month, the Taliban welcomed US President Donald Trump's tweet that all US troops should be "home by Christmas" – well before the May 2021 time table agreed in Doha. But on Thursday, Mr Trump's national security adviser Robert O'Brien said the number of US troops in Afghanistan would be cut to about 2,500 in the first two months of 2021. Clarifying the Trump administration's stance after conflicting accounts from the president, his advisers and the Pentagon, Mr O'Brien said US troop numbers would be at about 4,500 in the coming weeks, and further reductions would continue after that. "In the early part of next year we're going to be down to 2,500 troops," Mr O'Brien told an online conference of the Aspen Security Forum.