KABUL - Patrick Shanahan, the acting secretary of defence, has arrived in Afghanistan on an unannounced visit amid a push by the United States to negotiate peace with the Taliban.

Shanahan will meet Afghan President Ashraf Ghani, whose government was not part of major talks between the US and Taliban officials last month that officials hope could bring a breakthrough in the 17-year conflict.

"It is important that the Afghan government is involved in discussions regarding Afghanistan," Shanahan told a small group of reporters travelling with him on the surprise trip on Monday.

The acting Pentagon chief said Washington has important security interests in the region and wanted to hear from the commanders on the ground.

Shanahan replaced Jim Mattis, who quit in December over policy differences with US President Donald Trump.

The Taliban has refused to negotiate directly with Ghani's government, calling it a "puppet" of the West. But Ghani's allies in Washington insist Afghans should lead the peace process.

Kabul is also concerned that a sharp withdrawal of the nearly 14,000 US troops in Afghanistan could lead to chaos in the region.

The Taliban wants all American troops withdrawn, and officials say that is at the top of the armed group's list of demands in exploratory talks.

Shanahan, who will also meet US commanders, told reporters he had so far not received any direction to reduce troops in Afghanistan.(FA)