NATO is set to take command of some of the US-led coalition operating in Iraq.
The decision was taken in principle during a defence ministers meeting in Brussels on Wednesday.
Discussions are ongoing about how to increase the alliance's role.
It was widely known the United States wanted to step back from leading their Global Coalition activities in Iraq and thought NATO should do more.
"In the first instance, this will consist of taking on some of the Global Coalition's current training activities," NATO Secretary General Jens Stoltenberg said.
"Ministers also agreed to explore what more we can do beyond this first step.
"Let me be clear, NATO is in Iraq on the invitation of the Iraqi government, and we will only stay in Iraq as long as we are welcome," he added.
The decision appears to be a significant increase in what the alliance does in Iraq.
Their mission, which began in 2018 and involves training and mentoring the Iraqi military, remains suspended following security concerns in the country last month.
The number directly under NATO command will now increase, encompassing at least some of the 5,200 US personnel currently operating in the country.
However, it is believed the nationalities of those in the country may change, raising questions about whether more British personnel might be deployed there.
Britain currently has around 400 personnel operating in Iraq - a small number for NATO already.
They have seen success training and mentoring Iraqi and Kurdish security forces.
Speaking to Forces News before the decision was made for NATO to take command of the international mission, Defence Secretary Ben Wallace said: "We will do whatever the Iraqis request us.
"We think it's really important to be in Iraq really to help the nation build, to improve their security by helping them deliver their own security," he added.
Also on Thursday, there was news of a possible seven-day reduction in violence in Afghanistan in a deal brokered by the US in talks with the Taliban, but no further details were given.
There were also discussions behind closed doors about encouraging member states to share the cost burden of NATO membership.
There was lots to be said on China, 5G and alleged spying.
US Secretary of Defence, Mark Esper made clear his advice to countries who have said yes to Chinese companies, such as Huawei becoming involved in the 5G rollout.
"At the end of the day Chinese telecom firms have a legal obligation to provide technical support and assistance to the Communist Party, and that concerns us deeply," Dr Esper said.
"Reliance on Chinese 5G vendors could render our partners' critical systems vulnerable to disruption, manipulation, and espionage," he said.
Speaking on Thursday, ahead of his return to London, Mr Wallace said there was a notable contrast in opinions.
"The British and the Americans on Huawei obviously have a difference of opinion, however, we both agree that our ambition is to ban them from the sensitive parts of our network, cap their contribution to the wider network and indeed, aim to cut them out of our networks in the long term," he said.
Many of those who attended the talks in Brussels are expected to be in attendance at the Munich Security Conference which begins on Friday.
Cover image: NATO Defence Ministers met in Brussels on Wednesday (Picture: NATO TV).