Fighting in Ukraine has continued with regularity despite an official ceasefire signed on Sept. 5. In particular, separatists have sought to gain control of Donetsk airport in eastern Ukraine and have launched repeated attempts to take control of it.

While the rise of ISIS and the spread of Ebola have made headlines recently, Americans should make no mistake: we have not heard the last from Russian President Vladimir Putin and Russian-backed separatists in Ukraine.

The U.S. needs to keep up the pressure on Russia’s leadership to abandon its support of separatists in Ukraine, while simultaneously developing a new strategy for tackling an increasingly belligerent and uncooperative Putin regime.

Separatists retain de facto control over portions of eastern Ukraine, and are likely to continue to try and extend their territorial control.  At least thirty Ukrainian soldiers have been killed since the official ceasefire, which NATO Supreme Commander General Philip M. Breedlove has called a “cease fire in name only,” took effect a month ago.

Today, Russian-backed separatists reopened attacks on Ukrainian forces holding the Donetsk airport, an assault that was reportedly rebuffed. With the winter months approaching, Russia is sure to seek to leverage its natural gas exports to Ukraine as a political weapon. While talks continue over Russian exports of natural gas to Ukraine, Russia recently threatened to shut off exports to European nations that send excess gas to Ukraine, a warning that may have been heeded by Hungary.

Russia’s support of the separatists in Ukraine has not abated since the ceasefire was signed. Russian troops and equipment continue to operate inside Ukraine, as confirmed by U.S. ambassador to Ukraine Geoffrey Pyatt. Additionally, Russia continues to hold hostages, including a Ukrainian filmmaker and service member and an Estonian security officer kidnapped by Russia on the Estonian side of the border.

While the U.S. and our allies are distracted by challenges including Islamic terrorists, and dangerous diseases, the crisis in Ukraine has not gone away. The ceasefire that never was looks increasingly tenuous: Putin and his friends have not been deterred. The U.S. needs a strategy for dealing with Russia, and fast.