BRUSSELS (Reuters) - NATO leaders meet in Warsaw on Friday to cement a new deterrent against what they see as an emboldened Russia, returning to Cold War-style defence with Washington again taking the part of Europe's protector.
Britain's decision to quit the European Union, along with a migration crisis and Islamic militancy, leaves U.S. President Barack Obama seeking a show of unity at his last alliance summit to fend off accusations that NATO is obsolete and to dampen any Russian perceptions of weakness in the Western camp.