After observing a "continuous steady flow" of equipment and people into Syria, the Pentagon acknowledged Monday that Russia has been building up a military base in that war-torn country, NBC News reports.
Pentagon spokesman Captain Jeff Davis would not comment on whether the coalition has invited Russia to join the air campaign against ISIS in Syria. He said the US is worried only about "deconfliction" of airspace over Syria.
Russia has called for a military-to-military cooperation with the United States to avert "unintended incidents" as it stages navy exercises off the coast of Syria, where U.S. officials believe Moscow is building up sources to protect President Bashar Assad.
