NATO Secretary-General Jens Stoltenberg said on Tuesday that the alliance was ready to answer a U.S. call for NATO to expand its small training mission in Iraq to support reconstruction of the country after three years of war with Islamic militants.

"We have to win the peace," Stoltenberg told a news conference, saying he expected NATO defence ministers to start planning for a bigger mission at a meeting in Brussels on Thursday, with a final decision seen for July.