The US is to cut its number of troops in Afghanistan and Iraq by 2,500, the US Department of Defense has confirmed.
President Donald Trump had previously warned that he would be cutting the size of US forces in the two countries.
The cuts will take effect before President Trump leaves office, the Pentagon said.
The Secretary-General of the Nato alliance, Jens Stoltenberg, has warned of a "high price" if US and allied forces leave Afghanistan too quickly.
In a statement, he said the country risked once again becoming a platform for international militants to organise attacks.
Nato currently leads a mission to train and advise the Afghan security forces. From 2003 to 2014, it ran a combat mission in Afghanistan with 130,000 soldiers at its peak.
In Iraq, the number of US troops will be cut by 500 to 2,500, while the number of service personnel in Afghanistan will fall from 4,500 to about 2,500.
Acting US Defense Secretary Chris Miller said the move reflected Mr Trump's policy "to bring the wars in Afghanistan and Iraq to a successful and responsible conclusion and to bring our brave service members home".
Shortly after the announcement, several rockets were fired into the Green Zone in Baghdad and landed near the US embassy. It is the first such attack since Iraqi militias linked to Iran agreed to stop targeting the embassy compound last month. There are no reports of casualties or any damage.