The meeting of Russian President Vladimir Putin and Chinese leader Xi Jinping in Moscow helped both give the impression of a united front, but underlying tensions were also discernible.

The Madrid summit paved the way for Finland and Sweden to join and underscored that Russia is NATO’s chief security threat. But the alliance’s new defensive efforts aren’t likely to change Putin’s st…

Russia has demanded security guarantees that U.S. and NATO officials cannot accept, but there could still be room for building a sustainable dialogue on European security.

President Putin’s deployment of troops in two separatist Ukrainian regions has nearly shut the door on diplomacy and intensified a showdown over European security.