Story highlights Two separate rocket attacks reported in the capital of Kabul

PM David Cameron tweets "today sees the end of combat operations"

Soldiers lower UK and U.S. flags at the UK's last remaining base in Helmand province

UK troops moved to Helmand province in 2006 to fight an insurgency

Britain formally ended its combat mission in Afghanistan on Sunday, lowering the Union Jack for the final time before handing over its last remaining base to Afghan forces.

"I made a commitment that I would get our Armed Forces out of Afghanistan by 2015, and today sees the end of combat operations in the country," Prime Minister David Cameron tweeted on Sunday.

American troops also took part in the ceremony at the Bastion-Leatherneck coalition base in Helmand province, marking the end of 13 years of UK military operations in the country.

Britain's military presence moved to Helmand in 2006 to tackle an insurgency together with troops from the United States and other countries. A total of 453 UK troops have died in service in Afghanistan.

"We will always remember the courage of those who served in Afghanistan on our behalf and never forget those who made the ultimate sacrifice," said Cameron.

According to the Ministry of Defence, Afghan National Security Forces will take over the bases and all operations. The United Kingdom will continue to support them in their development.

Already, the country's military is handling most of its security needs.

"In June 2013, the 330,000-strong ANSF took assumed lead responsibility for security across Afghanistan and since then they have been responsible for 99% of operations," the ministry said.

Meanwhile, two rocket attacks hit the Wazir Akbar Khan neighborhood of Kabul, home to the American Embassy, reported Pajhwok News Agency and Tolo News, a CNN affiliate that cited Kabul police spokesman Hashmat Stanekzai. There were no known casualties.

Also, two rockets landed outside the NATO-led International Security Assistance Force in Kabul, confirmed ISAF spokesman Mike Hartnett, speaking to CNN by phone. Hartnett said the attacks resulted in no ISAF casualties.