The U.S. army's chief of staff says he believes more troops are needed in Afghanistan.
General George Casey said in a U.S. television interview - NBC's Meet the Press - Sunday additional forces are needed to cut the Taliban's successes and train Afghan security forces.
He did not say how many more troops should be sent to the war.
U.S. President Barack Obama has been deliberating for weeks whether to deploy 40,000 more troops to Afghanistan, as requested by General Stanley McChrystal, the commander of U.S. and NATO forces there.
Britain's military chief Jock Stirrup said Sunday Washington's delay has caused frustration in London.
He told British radio (BBC) the current strategy requires more force. Without that, he said, London would have to "think again." He did not elaborate.
Stirrup said he does not believe Afghan forces will be able to take over the security of their country until 2014, a year later than U.S. estimates.
He said the 2013 timeline described by General McChrystal was "optimistic."
On Sunday in Afghanistan, police say suspected militants attacked a supply convoy for NATO forces, setting two fuel tankers on fire. Police say two security guards were wounded in the attack near Jalalabad, along the highway between Pakistan and Afghanistan.
Also Sunday, the Afghan Defense Ministry said Afghan and NATO forces killed 17 militants in southern Zabul province Saturday.
NATO says a separate joint force killed several other suspected militants in Kandahar province Saturday. It also says one U.S. service member was killed in an insurgent attack in western Afghanistan.
Britain's Defense Ministry separately confirmed that two of its soldiers died In southern Afghanistan's Helmand province. That brings the British death toll to 232.
Some information for this report was provided by AFP and AP.