The U.S. ambassador to NATO says America is committed to staying its course in Afghanistan until 2014.

But whether cash-strapped European nations feel the same at an upcoming Chicago summit in May is another question, The Associated Press reports.

Ambassador Ivo Daadler said Monday, Jan 23, the summit will focus on NATO's strategy in Afghanistan, costs and the alliance's capabilities. He said its planned missile defense system will go forward with or without the cooperation of Russia.

Daadler also spoke about Iran, saying international isolation may force Tehran back to the bargaining table.

The EU on Monday banned the purchase of Iranian oil. Iran responded, threatening to close the Strait of Hormuz, through which a fifth of the world's crude is transported.