U.S. President Barack Obama has said this weekend's NATO summit in Lisbon will be an important opportunity to align the allies' approach to the transition in Afghanistan.
Obama was speaking after his arrival in Lisbon to participate in the two-day summit, expected to focus on a timeline for reducing the number of foreign troops in Afghanistan.
NATO chief Anders Fogh Rasmussen speaking to journalists in Lisbon, called it "one of the most important summits in the history of our alliance. So I look very much forward to a successful summit."
Reports say the NATO leaders are expected to endorse Afghan President Hamid Karzai's proposal that Afghan forces will aim to assume the lead responsibility for security in the country by the end of 2014.
The 140,000 foreign troops are expected to start leaving Afghanistan from next year.
The NATO summit is also expected to unveil a new "strategic concept" -- a mission statement for the next decade aimed at countering threats including cyber attacks and terrorism.
Russian President Dmitry Medvedev is due to attend the summit to discuss Russia's involvement in expanding NATO supply routes to Afghanistan, and Russia's possible involvement in a missile shield.
compiled from agency reports