Air India said on Monday it would stop services between the capital cities of India and the US from September 1, citing aircraft shortage due to the planned upgrades to its aging Boeing planes and the closure of Pakistan’s airspace.

The suspension of services between New Delhi and Washington, D.C., marks the latest setback for Air India, which is facing heightened regulatory scrutiny after a June crash in Ahmedabad killed 260 people.

The planned shortfall in Air India’s fleet and continued closure of airspace over Pakistan have impacted the airline’s long-haul operations, leading to longer flight routings and increased operational complexity, the carrier said.

The airline has undertaken a $400 million retrofit program to upgrade its fleet.

It, however, sees the Pakistan airspace ban costing it $600 million over 12 months, Reuters had earlier reported.