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By Phil Stewart and Jason Lange
WASHINGTON/ISLAMABAD, Sept 7 (Reuters) - U.S. President Donald Trump on Saturday said he canceled peace talks with Afghanistan's Taliban leaders after the insurgent group claimed responsibility last week for an attack in Kabul that killed an American soldier and 11 other people.
Trump said he had planned a secret meeting with the Taliban's "major leaders" on Sunday at a presidential compound in Camp David, Maryland. Trump said he also planned to meet with Afghanistan's president.
But Trump said he immediately called the talks off when the insurgents said they were behind the attack.
"If they cannot agree to a ceasefire during these very important peace talks, and would even kill 12 innocent people, then they probably don't have the power to negotiate a meaningful agreement anyway," Trump said on Twitter.
The surprise announcement left in doubt the future of the draft accord worked out last week by Zalmay Khalilzad, the special U.S. envoy for peace in Afghanistan, for a drawdown of thousands of U.S. troops over the coming months.
There was no immediate reaction from the Taliban but the decision appeared to catch them by surprise.
Just hours before Trump's tweet, a senior Taliban leader privy to talks in Doha with U.S. officials including Khalilzad and Taliban chief negotiator Mullah Abdul Ghani Baradar, said an agreement to sign the deal appeared close.
Taliban fighters, who now control more territory than at any time since 2001, launched fresh assaults on the northern cities of Kunduz and Pul-e Khumri over the past week and carried out two major suicide bombings in the capital Kabul.
One of the blasts, a suicide attack in Kabul on Thursday, took the life of U.S. Army Sergeant 1st Class Elis A. Barreto Ortiz, 34, from Puerto Rico, bringing the number of American troops killed in Afghanistan this year to 16.
A spike in attacks by Taliban insurgents in Afghanistan has been "particularly unhelpful" to peace efforts there, a senior U.S. military commander said on Saturday as he visited neighboring Pakistan, where many Taliban militants are based.
U.S. Marine General Kenneth McKenzie, who oversees American troops in the region, declined to comment on the diplomatic negotiations themselves but criticised a wave of Taliban violence that has cast a long shadow over the deal.
"It is particularly unhelpful at this moment in Afghanistan's history for the Taliban to ramp up violence," McKenzie, head of U.S. Central Command, told reporters traveling with him.
McKenzie said for the peace process to move forward, "all parties should be committed to an eventual political settlement" which, in turn, should result in reduced violence.
"If we can't get that going in, then it is difficult to see the parties are going to be able to carry out the terms of the agreement, whatever they might or might not be," McKenzie said.
Under the draft accord, some 5,000 U.S. troops would be withdrawn over the coming months in exchange for guarantees Afghanistan would not be used as a base for militant attacks on the United States and its allies.
However, a full peace agreement to end more than 18 years of war would depend on subsequent "intra Afghan" talks involving officials and civil society leaders as well as further agreement on issues including the remainder of the roughly 14,000-strong U.S. forces as well as thousands of other NATO troops.
The Taliban have rejected calls for a ceasefire and instead stepped up operations across the country and it remains unclear whether they will accept direct negotiations with the Afghan government, which they consider an illegitimate "puppet" regime.
NEW CIVIL WAR?
For Afghans, the Taliban's recent escalation of attacks has underscored fears it may be impossible to reach a stable settlement following any complete U.S. withdrawal.
Ghani dismissed the talks as "meaningless" following Thursday's suicide bombing and his spokesman said an official reaction to Trump's announcement would come soon.
The Taliban's strategy appears to be based on the assumption that battlefield success would strengthen their hand in future negotiations with Afghan officials. Some of their field commanders have also said they are determined not to surrender gains when they are close to victory, suggesting the leadership is under internal pressure not to concede a ceasefire.
But that has risked undermining acceptance of the deal by Washington and its NATO allies as well as by Kabul.
"The Taliban's leaders will have to show they can stop the attacks, if not, then what is the point of holding long negotiations with Baradar?" said one Western diplomat in Kabul.
Even within the Taliban ranks, there appears to be doubt about how any agreement would take effect, given growing opposition to the deal from the government side.
"Don't ask me how to implement the peace accord," the Taliban official said.
Memories of the bloody 1990s conflict between the Taliban and rival militia groups are vivid. Former U.S. envoys who worked on Afghanistan warned last week that "total civil war" with "catastrophic" consequences for U.S. national security was possible.
Many have worried about a fracture along ethnic and regional lines, with Persian-speaking Tajiks and Hazaras from the north and west against southern and eastern Pashtuns, the group that have supplied most of Afghanistan's rulers and where the Taliban draw most support.
Some Taliban are based in neighboring Pakistan, where McKenzie held talks on Saturday with a top Pakistani general. More talks are scheduled for Sunday.
McKenzie said he did not know whether any of the planning for the recent wave of attacks in Afghanistan came from Pakistan-based militants.
But McKenzie commended Pakistan for supporting the peace efforts in Afghanistan, in the latest sign of an improvement in long-fraught relations between Washington and Islamabad.
"A lot of Pakistanis have been killed by militant attacks inside Pakistan. I think Pakistan sees the benefits of a stable Afghanistan," McKenzie said. (Additional by Jibran Ahmad in Peshawar, Rupam Jain and James Mackenzie in Kabul Editing by Marguerita Choy, Chris Reese and Michael Perry)