On that point, both major candidates have gaps: Hillary Clinton has said little about Afghanistan and nothing about future troop deployments, while Donald Trump has been characteristically self-contradictory. "This is neither the reduction that the White House seems to have wanted nor the current numbers that don't seem to be sufficient to deal with the security problem". "We will make sure that we use our strength, including through North Atlantic Treaty Organisation, to spread British values and the things that we believe in", Mr Cameron added.
There are still 450 British troops in Afghanistan, who had been due to return the the United Kingdom at the end of this year but will now have their tours extended into next year.
It may also be noted that since the US forces formally ended the combat mission in Afghanistan Taliban fighters have gained more territory and the Islamic State group has also established a small presence in the country. It acknowledges the threat not just from a resilient Taliban insurgency and an al-Qaida that shows signs of regrouping, but also the attempts by the Islamic State to make Afghanistan its latest seedbed for terror.
The NATO decision, however, relied on the USA remaining in Afghanistan to provide security, logistics and other support for the allies, particularly German troops working with Afghan forces in the north and Italian troops doing the same in the west.
Obama took office in 2009 pledging to wind down the war in Afghanistan - the longest in United States history.
But by October 2015, Obama reported that "Afghan forces are still not as strong as they need to be", while "the Taliban has made gains". If and when the USA does leave Afghanistan, the timing should be prompted by clear evidence that Afghans can achieve a lasting political resolution.
Obama will attend meetings in Warsaw on Saturday before heading to Spain for meetings with Spanish leaders and a visit with US troops.
Stoltenberg continued: "We call on Moscow to end its military, political and financial support for separatists". Obama pointed out that 38 Americans had died in the past 18 months.
Pointing to a 2017 timetable for Australian defence chiefs to revise the role and number of Australian troops in Afghanistan, a spokesman for Defence Minister Marise Payne said "that is a decision for further down the track".
Ghani's efforts to get the Taliban to engage in peace talks have been mostly fruitless, and the Afghan public has started losing patience as security worsens.
"Britain is not going to be playing a lesser role in the world".
Speaking at a joint news conference with Ukrainian President Petro Poroshenko, NATO Secretary-General Jens Stoltenberg said Russian Federation must stop its "political, military and financial support for separatists" in east Ukraine.
On Wednesday, President Barack Obama scrapped plans to cut American forces in Afghanistan by half before he leaves office in January.
He warned: "This troop reduction, while it will seem small to many, will have a negative impact on the security situation in Afghanistan".