Syrian airbase in the center of a potential Israeli-Iranian war

lying in the barren Sands of Central Syria and measuring five miles across in some areas is the largest airbase of the country. A fortress surrounded by hundreds of miles of desert, T-4 consists of dozens of hardened aircraft shelters, hiding Russian fighter jets and supersonic Sukhoi bombers.

Over seven years of conflict its runway has been blackened by the rubber tyres of jets returning from sorties in the devastating war between the forces of Bashar al-Assad and the rebels who have failed to overthrow him.

T-4’s remote location and Soviet-era fortifications have shielded it from much of the violence that has laid waste to Syria, though it bears the scars of a 2016 Islamic state artillery attack that obliterated four combat helicopters.

Today, the base is the focus of an emerging, potentially catastrophic war, fought not between the Syrian regime and its domestic foes, but two of the region’s most formidable enemies: Israel and Iran.

T-4 is where Iran has established a military foothold in its Arab ally. According to Israeli officials, Iranian drones used over Syria take off from the base.

Satellite images captured in April and acquired by the Guardian show what is believed to be the remains of a strike by Israel on Iranian forces stationed at T-4 – evidence of a direct confrontation between the two countries.

Taken 48 hours after what Russia and Syria said was an Israeli F-15 strike on T-4, the images show what appears to be the smashed frontside of a metal aircraft hangar. Seven Iranian military personnel were killed in the attack, Iran’s Tasnim news agency reported, which also published photos taken from the ground of what seem to be the same white hangar doors ripped apart by shrapnel.

Israel’s military had previously shared an aerial photo of a drone at T-4 exiting the same eastern hangar, indicating the structure was used for Iran’s drone operations.

“The chances of an escalation into a full-scale military conflict in Syria are higher than ever before,” Israel’s former military intelligence chief, Amos Yadlin, told the Guardian. “No doubt Iran is planning about the need, from their side, to respond. We’ll have to wait.”

Israel’s leader, Benjamin Netanyahu, has long sought to discredit Tehran, which he labels a “terrorist regime”. In an announcement on Monday, he claimed that Israeli intelligence had exposed Iran as lying about its nuclear weapons programme and adding to its “knowhow” after a 2015 nuclear deal. The presentation, which came less than two weeks before Donald Trump is due to decide whether to continue to abide by the 2015 deal by waiving US sanctions on Iran, offered no proof that Iran had violated the agreement since it took effect.

Since the start of Syria’s uprising in 2011, Israel has carried out at least 100 cross-border strikes, although they have always targeted Iran’s proxies, including weapons deliveries to Hezbollah, the Lebanese militant group. Historically, Hezbollah has also been the tool Iran has used to strike Israel.

But the consensus among the Israeli intelligence community is that Iran’s Islamic Revolutionary Guards corps (IRGC) is now tasked with a retaliatory attack, and Iran and its allies have publicly warned of an escalation.

Hezbollah’s leader said the T-4 airstrike was a “historic mistake” and put Israel in a state of “direct confrontation” with Iran. “This is unprecedented in seven years: that Israel directly targets Iran’s Revolutionary Guards,” Hassan Nasrallah said.

Ali Shirazi, a representative for Iran’s supreme leader, Ayatollah Ali Khamenei, threatened retaliation. “If Israel wants to continue its treacherous existence … it should avoid stupid measures,” he said, according to the Fars news agency. “Iran can destroy Israel.”

Israel’s view is that Iranian military support to Syria during the war has mushroomed to include significant amounts of arms, at times disguised as humanitarian assistance, as well as combat troops. From 2015, military cargo planes marked as civilian were regularly used to fly in personnel from the Mehrabad airfield in Tehran. Advanced weapons systems, including drones, were also brought over.

Specialist Iranian unmanned aerial vehicle (UAV) operators were stationed at the international airport in Damascus but gradually moved to bases around the country. These forces are believed to be working out of Damascus, Aleppo, the Sayqal airfield near the capital, the eastern Deir ez-Zor base and, mostly notably, T-4.

“To begin with, Tehran’s goal was limited to keep the Assad regime in power and secure the overland corridor from Tehran to Lebanon,” said Ali Alfoneh, a researcher at the Atlantic Council who tracks Iran’s presence in Syria.

“However, as those goals were achieved, the Islamic Republic is considering how to maintain a low-intensity conflict with Israel, with the aim of keeping Israel busy and increasing the cost of potential Israeli raids against Iran in the future.”

Iran’s foreign minister, Mohammad Javad Zarif, has denied Iran operated drones inside the country, and says T-4 is not an Iranian base. However, an Israeli military source said there were still drones at the base. “We definitely know there are Iranian UAVs at T-4,” the source said, without specifying numbers.

April’s strike was the second such mission on T-4 by Israel.

In February, it downed another Iranian stealth drone, which Israel later said was armed with explosives. Breaching Israeli airspace, the drone marked the first time Iran directly attempted to move against its long-time adversary, which immediately retaliated, including with a strike on T-4.

Unlike the February attack, the April strike was pre-emptive rather than reactive. In a game of tit-for-tat, Iran is expected to make the next move.

In what has been interpreted as an attempt to ward off Iran from any reprisals it is planning, black and white photographs of bases in Syria where Iranian forces are operating were released last month to the Israeli and foreign press.

According to the military correspondent for Israel’s Haaretz newspaper, the message to Iran was clear: “Your military is transparent to Israeli intelligence and is therefore very exposed to additional attacks.”

Whether the tactic worked is unclear. A missile attack on Sunday night, which Israel has not commented on but is believed to have targeted a depot for surface-to-surface missiles where Iranian forces are based, has further raised fears of a backlash.

Having Iran’s military operating from a country with which Israel shares a frontier would, in the words of Israel’s defence minister, be a “chokehold on us”.

In the Golan Heights, a plateau captured from Syria in 1967 and since occupied, the Israeli military has started to prepare itself for the possibility of an interstate border war, a situation the small country has not had to face for decades.

Syrian homes built from the black volcanic rock, long abandoned, dot the landscape, as do minefields – a reminder of a history of conflicts many Israelis hoped they had left behind.

Cows munch on grass in fields cleared of ordnance, weekend hikers walk along roads lined with eucalyptus trees, and old Israeli army lookout posts from wars in 1967 and 1973 have been converted to tourist attractions, with views of Syria to the east and Lebanon to the north. Children play hide and seek in old bunkers.

A ground offensive from Iran feels like a remote possibility, and it is anti-Iran rebels who control the other side of the frontier, not Tehran-allied forces. Some believe Israel’s leadership is playing up the danger.

Even as two Israeli combat helicopters hover above, Asaf Mendel, 45, who had travelled up to the Golan with his wife and two young children, dismissed any immediate threat of war with Iran. It is unbelievable, he said.

“The government is frightening the people,” he said. “It’s not good that Iran is in Syria, but we have a strong army.”