By Dorian Jones

KIEV - Turkish President Recep Tayyip Erdogan's visit to Ukraine Thursday saw the countries deepen their defense industry cooperation. The growing ties come in the face of Moscow's criticism as Russian forces continue to mass on the Ukrainian border.

After signing eight agreements with Turkish President Recep Tayyip Erdogan, Ukrainian President Volodymyr Zelenskiy declared that the defense and aviation industries were the main driving forces behind the country's strategic partnership.

During Erdogan's Kyiv visit, a commitment was made to expand the production of Turkish drones in Ukraine and to construct a drone pilot training center and factory.

Moscow has vehemently criticized Ankara's sale of Turkish drones to Ukraine, which were used in October against Russian-backed rebels in the Donbas region. But Asli Aydintasbas, a senior fellow at the European Council, says Turkey is also a big winner because of its deepening relationship with Ukraine.

"Turkey does sell drones to Ukraine, that is true, even at the risk of angering [Russian President] Vladimir Putin sometimes," said Aydintasbas. "But it also gets very significant know-how from the Ukrainian defense industry, particularly on how to make engines. This is one thing Turkey's very ambitious defense industry lacks, whereas Ukraine was an important production base during Soviet times."

Ukraine is a world leader in military-engine production, from powering drones to jet engines to missiles, a legacy of the time when Ukraine was part of the former Soviet Union, says Petro Burkovskiy, a senior fellow at the Democratic Initiatives Foundation in Kyiv. Burkovskiy says accessing that expertise has become a center of an international power struggle.

"We have a huge factory, which during Soviet times and after the collapse of the Soviet [Union], supplied engines. The Chinese tried to buy this factory, and this contract was frozen by Ukrainians, and also the United States objected because it would increase the military capabilities of China," said Burkovskiy. "The same plant is the key partner in this Turkish-Ukrainian venture to develop the drones and supply engines to the drones."

Turkey also is seeking engine expertise in developing its own fighter jet and jet-powered drones. A prominent Turkish military helicopter deal collapsed recently with Pakistan over restrictions by Washington on the use of American engines. Defense analyst Arda Mevlutoglu says Ankara now sees Ukraine as an essential alternative to traditional western military suppliers.

"Turkey tries to diversify its sources because traditionally, Turkish defense manufacturers have been reliant on the United States and European manufacturers. But mainly due to do political relations and sanctions, Turkey has been facing problems procuring technology and components from western countries," said Mevlutoglu. "Therefore, these factors make Ukraine a very important alternative compared to European and Unified States manufacturers."

Turkey's deepening cooperation with the Ukrainian defense industry continues to draw criticism from Russia. For now, though, Ankara appears more than ready to pay that price for access to Ukraine's expertise.