The six Leopard 2A4 tanks Spain has promised to send to Ukraine will leave the country in the second half of April, Defence Minister Margarita Robles told state broadcaster TVE on Wednesday, pushing back the estimated shipment date, Reuters reported.

“The German-made battle tanks have not been used since the 1990s and had been mothballed in reserve, requiring refitting and battle readiness tests after initial doubts as to whether they could go into combat again,” the agency notes.

Spain had committed to sending a total of 10 tanks to Ukraine, and Robles said the armed forces had started repairing the remaining four.

It has also trained 40 tank crew members and 15 mechanics at a military base in the northeastern city of Zaragoza.