WASHINGTON — The United States on Monday voiced "confidence" in Afghanistan's upcoming traditional assembly (loya jirga), saying it trusted the meeting would affirm close US-Afghan ties.

In Kabul just hours earlier, a suspected suicide bomber carrying a bag of explosives was shot dead near the site of the major meeting of Afghan elders set to discuss relations with the US, officials said.

The man was gunned down and two accomplices arrested in Kabul, hours after the Taliban claimed to have published a top-secret security plan for the loya jirga, which starts Wednesday and will bring together more than 2,000 elders.

"The US and Afghanistan are -- are close partners and allies, and we have great confidence that -- that this loya jirga is going to reaffirm that strong partnership," Mark Toner, a State Department spokesman, told reporters.

Toner did not comment on the incident in Kabul.

"The loya jirga itself is a traditional Afghan institution for which we have the utmost respect," he said.

And "in terms of security, you know, I'd have to refer you to the government of Afghanistan regarding security efforts surrounding the meeting."

Ten years after the start of the war, about 97,000 US soldiers and 45,000 coalition troops are still deployed in Afghanistan.

The loya jirga will discuss the US-Afghanistan strategic partnership, which is still under negotiation but will govern the two countries' relations after 2014, when all foreign combat troops are due to leave.

In late 2010, leaders of NATO countries including the United States, including US President Barack Obama, decided to transfer full responsibility for security in Afghanistan to its own forces in late 2014.

So far, Obama has announced the withdrawal by summer 2012 of "surge" forces sent in as a reinforcement in late 2009 -- about 30,000 troops.