(Reuters) -Air Lease Corp on Thursday reported a quarterly loss after the aircraft lessor recorded a previously announced $802.4 million charge on the value of jets stranded in sanctions-hit Russia.

Global aircraft leasing companies have been scrambling to repossess more than 400 jets worth almost $10 billion from Russian airlines, which have mostly been unresponsive to demands for surrendering the jets.

“While we wrote-off our Russia exposure, we are vigorously pursuing our insurance coverage and believe we have strong and valid claims,” said Air Lease Chief Executive John Plueger.

Air Lease said last month it would write off the value of the 27 jets it has remaining in sanctions-hit Russia – 21 company-owned jets and six aircraft in Air Lease’s managed fleet.

The aircraft stuck in Russia represent about 3.4% of the company’s fleet by net book value, as of March 31.

The company reported net loss of $479.4 million, or $4.21 per share, in the three months ended March 31, compared to a profit of $80.2 million, or 70 cents per share, a year earlier.

Revenue rose 25.7% to $596.7 million in the quarter.

Los Angeles-based Air Lease, the largest U.S. aircraft financier, said air travel demand was driving the need for both new and young used aircraft, supporting higher lease rates and boosting the value of jets in its fleet.

For Airlines, leasing aircraft reduces upfront capital costs, conserving cash while also offering fleet flexibility.

Air Lease said it took delivery of eight new and one used aircraft in the quarter, representing roughly $490 million in aircraft investments.

It had 370 aircraft in its owned fleet, with a net book value of $22.3 billion, it said.

(Reporting by Eric M. Johnson in Seattle and Aishwarya Nair in Bengaluru; Editing by Shailesh Kuber and Lisa Shumaker)