Clashes broke out between Ukrainian troops and armed separatist in the country’s east, killing at least 6 people in Donetsk, despite the ongoing ceasefire.
According to reports, the Ukrainian military blamed rebels who launched an attack on the city’s airport.
The US military meanwhile is set to commence peacekeeping exercises in the west of Ukraine, with another 15 countries.
The US defence department announced earlier this month that 1,300 personnel, including 200 soldiers, would take part in the exercises.
Ukrainian President Petro Poroshenko is due to visit the White House later this week, where he is scheduled to meet US President Barack Obama.
A White House spokesman they will discuss diplomatic ways to end the crisis and that the talks will stress U.S. commitment to "stand with Ukraine" in its pursuit of democracy and stability.