Image copyright EPA Image caption The US is deciding whether to bolster its Afghan effort, as the security situation deteriorates

As the White House mulls its next move in conflict-hit Afghanistan, the Taliban offer their advice in an open letter to the US president.

Donald Trump is, as the world knows, happy to talk about all sorts of things, but one area where he has maintained his silence is American policy in Afghanistan.

His military advisers concede that America's longest-ever war has reached a stalemate and have advised that he increase troop numbers to break it.

In the past, Mr Trump has hinted that his instinct is to cut America's losses and begin to pull back from the conflict. Meanwhile, the world awaits a decision.

We were told the White House would make its call by mid-July, but there has been silence. Then last week, Mr Trump announced he was "getting very close" to deciding on a strategy.

"I took over a mess," the US president acknowledged, "and we're going to make it a whole lot less messy."

He has now got some advice from an unexpected quarter - the Taliban. The hard-line Islamic group tagged him on his medium of choice, Twitter, urging him to heed their thoughts on this fraught issue.

"We have noticed that you have understood the errors of your predecessors," says the official press release from the insurgent organisation, "and have resolved to thoroughly rethink your new strategy in Afghanistan".

It warns him not to listen to what it calls the "warmongering congressmen and generals", and not to "protract the war". Not surprisingly, the Taliban's advice is that the wise solution would be "a complete withdrawal".

"On the one hand, this strategy will truly deliver American troops from harm's way," the insurgents explain, "and on the other, it will bring to an end an inherited war by rectifying the mistakes of former American officials".

The 16-year US military presence had made Afghanistan less stable and more corrupt, the Taliban added.

Image copyright Reuters Image caption The Taliban have carried out major attacks in recent months, like this one in Kabul's green zone in May

Image copyright Reuters Image caption Across the country, civilian deaths are at a high - the rise largely attributed to the Taliban

In recent months the Taliban have been steadily extending their reach in Afghanistan. They are now believed to control at least 10% of the country and contest another third. Al-Qaeda and the so-called Islamic State militant group are also both active.

The Taliban have launched a series of major attacks this summer, with a huge bomb in the diplomatic district of the Afghan capital, Kabul, in May. A month earlier, at least 140 Afghan soldiers were killed in a Taliban attack on an army base near the city of Herat.

The Afghan government, meanwhile, is regarded by many as weak and divided, a point the Taliban seek to drive home to Mr Trump. "The only thing they hold dear is retaining their seat of power and securing their personal interests," the insurgent group warns.

The Taliban Shura - the leaders of the movement - appear sensitive to the arguments that will be playing on the American president's mind.

Media playback is unsupported on your device Media caption Justin Rowlatt visits the site of the army base attack in Herat

"American youth are not born to be killed in the deserts and mountains of Afghanistan in order to establish the writ of thieves and corrupt officials," says the missive.

It warns against the use of private military contractors - an option which has been discussed by senior White House advisers - and urges Mr Trump to reflect on history as he decides his next move, asking how the US can achieve a stable presence "in a land where every child is raised with a spirit of vengeance".

Perhaps more surprising is an appeal to Mr Trump's sense of loyalty to a people who have "done you the biggest favour internationally" by rescuing the world from "the Red Communist Plague".

The letter assures Mr Trump that the Afghan people "have no ill-intention towards the Americans", but warns that they are good at defeating those who "violate their sanctums".

This is, by Taliban standards, a long and cogent intervention into the ongoing debate on American policy in Afghanistan. Whether Mr Trump will listen to these arguments is, of course, an open question.