American aviation major United Airlines on Thursday suspended flights between Newark and Mumbai amid rising tensions between the United States and Iran. The strained relationship between the two countries worsened during the day after Iran shot down an American spy drone near the Strait of Hormuz.

“Given current events in Iran, United Airlines Link has conducted a thorough safety and security review of our India service through Iranian airspace and decided to suspend our service between New York/Newark and India (Mumbai) beginning today evening,” United said in a statement, according to The Times of India.

Meanwhile, German airline Lufthansa said it was no longer flying planes over the Strait of Hormuz or the Gulf of Oman, AP reported. The airline said flights over the two water bodies were suspended on Thursday based on its own assessment of the situation. However, the carrier said its flights to Tehran will continue.

The airlines, however, did not specify how long the suspensions would last. A United Airlines spokesperson told Reuters that passengers flying to Newark from Mumbai will be booked on alternative flights.

Meanwhile, the United States Federal Aviation Administration on Thursday issued a notice prohibiting US airlines from operating over the Persian Gulf and Gulf of Oman. “The NOTAM [notice to airmen] warns pilots that flights are not permitted in the overwater area of the Tehran Flight Information Region until further notice, due to heightened military activities and increased political tensions that might place commercial flights at risk,” it said in a statement. “The NOTAM applies to all US air carriers and commercial operators.”

In another advisory to operators, the aviation regulator said a civilian aircraft was operating within 45 nautical miles of the drone that was shot down. “There were numerous civil aviation aircraft operating in the area at the time of the intercept,” FAA said, according to Reuters.

#FAA issued #NOTAM warning pilots that flights are not permitted in the overwater area of the Tehran Flight Information Region until further notice, due to heightened military activities and increased political tensions. https://t.co/BQ2GOeFSEn pic.twitter.com/4t1OWEzkYZ — The FAA (@FAANews) June 21, 2019

#FAA Statement: The FAA has issued a Notice to Airmen (#NOTAM) prohibiting U.S.-registered aircraft from operating over the Persian Gulf and Gulf of Oman. The NOTAM applies to all U.S. air carriers and commercial operators. pic.twitter.com/Z5eVX6hyOx — The FAA (@FAANews) June 21, 2019

Iran says drone was in its territorial waters

Earlier in the day, the United States accepted claims by Iran’s Islamic Revolutionary Guard Corps that it brought down the surveillance drone. However, the US said the drone was shot down in international waters and not over Iranian airspace.

The Pentagon claimed that the unmanned aerial vehicle was 34 km from Iran when it was destroyed, and published a map showing its flight map, which indicated that it was outside Iranian waters, AFP reported. It provided photographs showing the coordinates to support its claims.

Iran, however, said it had recovered some parts of the drone in its territorial waters. “We do not seek war, but will zealously defend our skies, land and waters,” Iran’s Foreign Minister Mohammad Javad Zarif said. The minister also provided coordinates to back Iran’s claim. “We have retrieved sections of the US military drone in our territorial waters where it was shot down.”

Zarif’s deputy Abbas Araghchi told Swiss ambassador Markus Leitner, whose country represents American interests in the West Asian country, of the evidence, AFP reported. Araghchi urged US forces to “respect Iran’s aerial and maritime borders and fully abide by international regulations”. He “reiterated that Iran does not seek war in the Persian Gulf, and warned American forces against any “unconsidered measure in the region”.

United States President Donald Trump said “Iran made a very big mistake” in shooting down the drone. Later, at the White House, he said: “This country will not stand for it, that I can tell you.”

But he dialled down the aggression in his later statements. “I find it hard to believe it was intentional, if you want to know the truth,” Trump said. “I think that it could have been somebody who was loose and stupid that did it.” On being asked about the US’ next move, he only said: “You will find out”. Trump reportedly approved military strikes on Iran but later changed his decision, according to The New York Times.

Last week, the United States had accused Iran of attacking two oil tankers in the Gulf of Oman. Iran has repeatedly warned it might block the Hormuz Strait in retaliation and denied its involvement in the attacks.

The tensions come in the backdrop of an escalating standoff between the US and Iran one year after Trump withdrew from the 2015 Iran nuclear deal, and reimposed heavy sanctions on the country. Iran responded to the sanctions by threatening to walk away from its obligations under the nuclear deal – which had promised economic relief in exchange for limits to its nuclear development – and return to higher levels of uranium enrichment.