(Reuters) – A flotilla of five tankers carrying Iranian fuel for gasoline-starved Venezuela is approaching the Caribbean, with the first vessel expected to reach the South American country’s waters on Sunday, according to Refinitiv Eikon tracking data.

Iran is supplying about 1.53 million barrels of gasoline and alkylate to Venezuela, according to both governments, sources and calculations made by TankerTrackers.com based on the vessels’ draft levels.

The shipments have caused a diplomatic standoff between Iran, Venezuela and the United States as both nations are under U.S. sanctions.

The OPEC-member country desperately needs fuel to feed up to 1,800 gasoline stations that have been partially closed for weeks due to insufficient supply from state-run PDVSA’s refineries, which until March worked at about 10% of their joint capacity of 1.3 million barrels per day (bpd).

Shipments of equipment in flights by Iran’s Mahar Air have arrived in Venezuela in recent weeks to start repair work.