Ukraine said 120,000 useless mortar rounds were sent to its front line after a manufacturer tried to cut costs

• Ukraine said it uncovered a conspiracy that ended with 120,000 bad mortar shells sent to its troops.
• Its security service said a defense plant had tried to cut costs by knowingly using cheap parts.
• Officials made four arrests as Ukraine remains hard-pressed to keep its ammo supplies flowing.

Ukraine's internal security bureau said on Tuesday that it had detained four people after investigating the supply of 120,000 defective mortar shells to its troops.

The Security Service of Ukraine, also known as the SBU, wrote on its Telegram channel that the persons arrested included a military official, a quality control official, and two heads of a defense manufacturing business.

The announcement comes six months after Ukrainian media reported complaints from some frontline units that their 120mm mortar shells weren't firing or would fail to explode.

In a video that went viral in November, one soldier said only about one in 10 rounds would make it out of its launcher and detonate effectively. At the time, Ukrainian journalists reported that up to 100,000 shells were due to be recalled.

The SBU said it investigated a defense plant in the Dnipropetrovsk region, home to the key city of Dnipro, and found that the four people arrested had conspired to "supply defective mortar shells to the frontline."

"For mass production, the suspects used substandard materials and performed faulty workmanship, causing the main charge primer to fail and resulting in unstable performance of the entire propellant charge," the SBU's statement said.

The security service did not name the arrested persons, but it accused all four of conspiring to "reduce production costs to increase their profits."

The SBU said the military and quality control officials "deliberately ignored" the defective ammunition and falsified records to cover up the scheme.

"Consequently, 120,000 unusable shells reached the front line," it added. If found guilty, the four detainees face up to 15 years in prison, the SBU said.

Artillery ammunition has been especially key to Ukraine's defense as the war has dragged into an extended battle of attrition. One of Kyiv's most pressing issues is the war's strain on the number of soldiers it can field at a time, and it faces a dilemma of whether to lower its draft requirements to include men as young as 18.

But Ukraine is also trying to prevent a shortage of ammunition, which Europe and the US have been working in overdrive to supply. Amid the rush, Kyiv has been trying to boost its local defense manufacturing scene, which is already cranking out millions of first-person view drones.