U.S. Secretary of State Marco Rubio and his NATO counterparts meet in Turkey to prepare a pivotal summit of alliance leaders next month that will set the course for future European security as America focuses on challenges elsewhere.

"I think there is this window of opportunity this week, but also in the next 10 days, two weeks, to really bring the whole issue of Ukraine to a better place," NATO Secretary General Mark Rutte said.

U.S. Secretary of State Marco Rubio will attend the informal NATO foreign ministers meeting in Turkey on May 14-16 to discuss ending the Russia-Ukraine war.