In the villages around the port city of Mariupol in southern Ukraine, pro-Russian rebels and Ukraine troops continue to exchange fire, as both sides accuse the other of using heavy artillery and tanks. The Ukrainian National Security and Defense Council has said that pro-Russian rebels are increasing their combat readiness in preparation for an attack on the port city of Mariupol. Should such an attack take place, the Minsk II agreement governing the current ceasefire would most likely collapse, leading the region back into a full-scale conflict.     

"According to intelligence reports, the leaders of the DPR have put their troops on full alert, calling on the militants to return back from health treatment in Crimea and Russia, as well as in other places," National Security and Defense Council spokesman Andriy Lysenko said at a briefing in Kiev on Wednesday, referring to the self-proclaimed Donetsk People's Republic.  

Mariupol’s location on the coast of Sea of Azov, which leads to the Black Sea and then the Mediterranean, makes it a strategically important city. Much of Ukraine’s steel industry is located in the region, and most exports leave through the port. Securing it would offer important financial revenue to assist the self-proclaimed Donetsk People’s Republic, should it actually try to capture the city.

Lysenko also denied claims by pro-Russian rebels that the Ukrainian military had breached the ceasefire 45 times in the past 24 hours, saying that “the enemy is actively spreading rumors about the beginning of active military” action by Ukraine’s troops.

The claims were made by the pro-Russian Donetsk News Agency, which said that several settlements around Mariupol had been hit by tank fire, mortars and small arms, as well as shelling, in recent weeks.  

"One person from the self-defense forces was killed in shellings, three more were injured," a spokesperson from the DNR's Ministry of Defense said, using the rebels' own term for pro-Russian forces in East Ukraine.

The organization charged with overseeing the Minsk II agreement, which was signed on Feb. 12 and went into force on Feb. 15, said Tuesday that pro-Russian rebels had fired at one of its vehicles on a highway around 20 kilometers (13 miles) from Mariupol. The group from the Organization for Security and Co-operation in Europe then attempted to approach a checkpoint on the highway on foot and was met with machine gun fire that reportedly hit the ground on either side of the group. 

The group was later allowed to pass but was guided away from roads leading into Mariupol.