The Ukrainian government and Russia-backed separatists both threatened on November 4 to stop their ongoing weapons withdrawal if they keep coming under attack.
Ukrainian Defense Council Chairman Oleksandr Turchynov said that five troops were wounded by separatist attacks on November 3 and that Kyiv will stop pulling back weapons if the attacks persist.
Both sides have been pulling back weaponry since a truce was declared on September 1.
Separatist leader Aleksandr Zakharchenko also threatened to start fighting again if Kyiv keeps violating the truce, the Donetsk News Agency reported.
Despite flareups of violence, the truce has largely held. Little progress has been achieved, however, to bring about a political settlement to the conflict, which has claimed more than 7,900 lives.
U.S. State Department spokesman John Kirby said Washington welcomes the recent pullback of some heavy weapons from the line of contact, but is disturbed by an uptick in cease-fire violations over the past two weeks.
"This violence endangers the cease-fire," he said. "We call on Russia and the separatists to end the violence."
Based on reporting by Reuters, AP, and Interfax