The attacks, the first in Tehran in more than a decade, came just over two weeks after Mr. Trump, with Saudi Arabia and its allies, vowed to isolate Iran. Iran has dismissed those remarks, made at a summit meeting in Riyadh, the Saudi capital, as a scheme by Mr. Trump to sell weapons to Saudi Arabia.
In the view of many in Iran, the Islamic State, also known as ISIS or ISIL, is inextricably linked to Saudi Arabia. ISIS ideologically, financially and logistically is fully supported and sponsored by Saudi Arabia they are one and the same, said Hamidreza Taraghi, a hard-line analyst.
Iran and Saudi Arabia are the leading nations on opposing sides of the Middle East split between Shiite and Sunni Islam. Iran has military advisers in Iraq and Syria, and it controls and finances militias in those countries and in Lebanon. Tehran also has some influence over the Houthis fighting the government in Yemen, and it often speaks out in support of Shiites in Bahrain, a majority group that Iran says is repressed by the Sunni monarchy.
King Salman of Saudi Arabia has accused Iran of spearheading global terrorism. Saudi officials say Iran is plotting to control the region. Saudi Arabia, an autocratic kingdom, also opposes Irans political ideology, which has a clerical supreme leader but also a president, Parliament and City Councils, chosen in elections in which both men and women can participate.
On Wednesday morning, only hours before the attacks in Iran, the Saudi foreign minister, Adel al-Jubeir, said that Iran must be punished for its interference in the region and called Tehran the worlds leading supporter of terrorism.
Iran, in turn, has long accused Saudi Arabia of backing terrorists in the region, saying that the kingdom had facilitated the rise of Sunni extremist groups such as the Islamic State and others in Iraq and Syria.
After Egypt, Saudi Arabia, the United Arab Emirates and other states cut ties with the gas-rich kingdom of Qatar on Monday, citing its support for Iran, Tehran rushed to fill the void, offering to send food and medicine.
One Iranian security official said the attacks had been a message from Saudi Arabia that was meant to teach Iran a lesson. He also said the assaults were intended to test Irans reaction.
Others questioned Tehrans decision to rise to the defense of Qatar. We are wrong to suddenly seek close ties with Qatar, said Saeed Laylaz, an economist close to the government. They have been bankrolling the Sunni terrorist groups, in the same way the Saudis have.
Raz Zimmt, a scholar at the Institute for National Security Studies at Tel Aviv University who specializes in Iranian affairs, said the attacks were unprecedented in that they had occurred in the heart of Tehran.
I have no doubt that the Iranian regime is going to blame ISIS and Saudi Arabia, since that serves the official Iranian position, he said in an interview on Israeli radio. Weve heard for the past two years, more or less, that if the Revolutionary Guards stop operating in Syria and Iraq, the terrorists are going to make their way into Iran. As far as theyre concerned, it doesnt matter if it was ISIS or wasnt.
While terrorist attacks have become relatively commonplace in Europe and in most of the Middle East, Iran had remained comparatively safe. During Mays election campaign, President Hassan Rouhani often pointed to that fact, lauding the countrys security forces and intelligence agencies for their vigilance.
The coordinated terrorist attacks on Wednesday brought such feelings of security to an end, one analyst said. Today, it was proved that we are vulnerable too, the analyst, Nader Karimi Joni, said. We must anticipate more attacks by the Islamic State, now that we are defeating them in Iraq and Syria, he added.
