The participation of five Arab nations in U.S.-led airstrikes in Syria gave Washington broad regional backing as the threat of Islamic State militants galvanizes the Middle East against a shared enemy.

Saudi Arabia, the United Arab Emirates, Qatar, Bahrain and Jordan all supported or participated in the military action against the extremist group, according to the U.S. Central Command.

Other nations, including Egypt, expressed support for the military action but were not directly involved.

Russia, a key ally of Syrian President Bashar al-Assad, called the attacks a violation of international law. But the state-run Syrian Arab News Agency (SANA) said the United States had informed Syria’s representative to the United Nations that it would carry out strikes.

A group of Bahraini fighter jets carried out airstrikes “against a number of selected targets of terrorist groups” alongside other Persian Gulf and allied air forces, Bahrain’s official state news agency said. “The strikes are part of the international efforts to protect regional security and global peace, it added.

The United Arab Emirates also said its air force took part in the strikes, according to the state-run WAM news agency.

Iranian President Hassan Rouhani, for his part, called for a “resolute fight” against Islamic State “terrorists” but said the American attacks in Syria “do not have any legal standing.”

Speaking in a meeting in New York with senior editors of news organizations, he noted that Syria had not agreed to the bombardment and said it was not carried out under the “rules of the United Nations.” He described the airstrikes as an “attack” on Syria.

“There is no cooperation between us and the United States” in the action against Islamic State, Rouhani said. He said Iran had been first to offer assistance to Iraq when the United States had set strict limits on its military involvement.

Asked about a coalition against the Islamic State, the Iranian president said: “Who is best qualified to lead such a coalition? . . . Is it possible to do so without knowing the Middle East region extremely well?”

The Islamic State, which has developed an elaborate media and propaganda wing, did not immediately comment on the expansion of airstrikes into Syria.

However, a video that surfaced early Tuesday shows John Cantlie, a British journalist who is being held hostage by the Islamic State, lecturing the West on what he describes as its misguided policies in the Middle East. In the video, the second in less than a week, Cantlie, 43, is seated at a desk and wearing an orange jumpsuit.

Prince Saud al-Faisal, foreign minister of Saudi Arabia speaks during a meeting in Jeddah. U.S. officials said Saudi Arabia, the United Arab Emirates, Qatar, Bahrain and Jordan participated in the military action against Islamic State. (Brendan Smialowski/AFP/Getty Images)

Cantlie, who made clear in the first video that he was speaking under duress, says that the United States and its allies are heading toward Gulf War III.

“Not since Vietnam have we witnessed such a potential mess in the making,” he says.

Unlike in other Islamic State videos showing the beheading of Western hostages, there is no violence, and Cantlie is not threatened.

It was not immediately clear exactly what role Persian Gulf nations played in the airstrikes. Officials in the gulf provided no details of the operations Tuesday, but the United States has access to air bases across the gulf’s Arab states, and the U.S. Navy’s 5th Fleet is based in Bahrain.

Jordan’s state news agency said its air force launched strikes on “a number of sites used by terrorist organizations to target the Kingdom.”

The rapid expansion of the Islamic State in Syria and across the border in Iraq has cut across the region’s Sunni-Shiite divides. Shiite-led Iran also opposes the Islamic State — and sent allied Iraqi Shiite militia units to take part in the fight — but has so far stayed out of international efforts to confront the militants.

Iraq’s prime minister, Haider al-Abadi, had asked the United States to expand its operations to Syria to prevent Islamic State fighters from regrouping in their strongholds there.

Outside Iraq and Syria, neighboring Jordan faces one of the most direct threats from the extremist group. The country’s northern and eastern borders have seen a major spike in incursion attempts and shooting incidents against army posts over the past two months, the state news agency said Tuesday.

“In the early hours of Tuesday morning, Royal Jordanian Air Force aircraft destroyed a number of selected targets used by terrorist groups to dispatch their members for terrorist attacks in the Kingdom,” the agency said, citing an unnamed air force official.

It did not specify that the attacks were carried out on Syrian soil. Border security and the safety of the Jordanian people are “non-negotiable,” it added.

Appearing on “60-Minutes” on Sunday, King Abdullah II said that with the security vacuum caused by the Syrian civil war, militants would be more challenging to eradicate in Syria than Iraq. Referring to the Islamic State leader known as Abu Bakr al-Baghdadi, the Jordanian king said it was “horrendous and so shocking” that he speaks in the name of Islam.

Persian Gulf nations, which face a less direct threat to their borders, are likely to be giving “regional legitimacy” to the U.S.-led missions, said Mustafa Alani, a security analyst with the Gulf Research Center.

Gulf leaders are likely to push for more U.S. support to Syrian rebels, who have been backed by Qatar, Saudi Arabia and others, he said.

Egyptian President Abdel Fattah al-Sissi on Tuesday expressed his government’s support for the international campaign against the Islamic State, according to the official Middle East News Agency.

He also called on the coalition to expand its mandate to fight all forms of extremism, the agency said.

The Egyptian air force did not participate in the strikes on Syrian territory overnight Monday. In an interview with the Associated Press published Sunday, Sissi said his government is “fully committed” to cooperating with international partners to fight terrorism in the region.

However, “we don’t want to limit the confrontation to only military and security measures,” Sissi told the AP.

Sissi has long sought international legitimacy for his widespread crackdown on the Muslim Brotherhood group in Egypt, portraying his moves against the Islamist opposition as a fight against terrorism.

Egypt has grappled with the rise of jihadist groups in the Sinai Peninsula in recent years. None of the militants have pledged their allegiance to the Islamic State. But in a statement released Monday on the eve of the U.S. strikes, Islamic State spokesman Abu Muhammad al-Adnani urged Egyptian jihadists to continue to fight the country’s security forces.

Russia on Tuesday condemned the airstrikes.

“The fight against terrorism in the Middle East and North Africa requires coordinated efforts from the entire international community under the U.N. aegis,” the Russian Foreign Ministry said in a statement. “Attempts to accomplish one’s own geopolitical tasks by violating other countries’ sovereignty fuel more tensions and destabilize the situation further.”

The Kremlin has indicated that it opposes the spread of the Islamic State, but top Russian leaders have said they worry that the U.S. actions may quickly turn into a broader attempt to dislodge Assad’s government. Russia is Assad’s primary international backer.

Martin Baron in New York contributed to this report.