TEL AVIV—President Donald Trump may think he’s projecting strength and determination with his tweets and, perhaps soon, some variation on limited strikes against Syria. But concern that the United States of Trump may abandon Israel just as the distance to Iran has shrunk from 1,000 miles to zero has gripped Jerusalem like a fever.

For more than three years, Prime Minister Benjamin Netanyahu has used every public opportunity to warn the world of the dangers of Iran’s escalating presence in Syria, now meters away from residential communities along Israel’s northern border.

But the issue seems tangential at best to the rest of the world watching the Twitter storms and Fox News-inspired tirades of the American president. One moment Trump is insisting he wants out of Syria altogether, the next he’s threatening not only Bashar al-Assad but the Russians with retaliation for the alleged chemical attack in a Damascus suburb last weekend. And maybe that convinces some Americans of his fury, but few people here, living in a famously dangerous neighborhood, would mistake that for staying power.

As a number of analysts have pointed out, “limited strikes” or “surgical strikes” do not contradict Trump’s wish to get U.S. troops out of Syria completely.

For Israel, says Alex Grinberg, an expert on the Mideast, Russia, and Iran at Tel Aviv’s Middle East Center for Reporting and Analysis, such American retribution is largely meaningless for Assad, Russian President Vladimir Putin, and Iranian Supreme Leader Ali Khamenei, as well as the widely deployed Iranian Revolutionary Guard Corps, the IRGC.

Even if Trump hits Syria with massive force, Grinberg said, “it won’t change the balance between the IRGC and other Iran-affiliated militias and Israel. Only a Russian retreat from Syria could aid Israel… Instead, Trump’s position could have a global impact: If he is serious about an American military withdrawal from Syria, it will be a real gain for Assad, Putin, and Khamenei.”

The level of Israeli anxiety, he estimates, “is about the same as it was” under President Barack Obama, when Netanyahu led the opposition to the U.S.-led nuclear deal with Iran.

On Tuesday, while visiting an emergency command center just a few feet away from the Syrian border, Israeli Defense Minister Avigdor Lieberman said that accepting a permanent Iranian military presence in Syria would amount to “agreeing to the Iranians placing a noose around our necks. We will not allow it.”

Alluding mainly to the United States and Europe, Lieberman said, “There are those who can stop it without using military force. “I hope [they] will act and do the right thing. It is in their power to prevent Iran from establishing itself [in Syria] without unnecessary friction.”

But what means the Trump administration might use to do that are something of a mystery with an American government so often distracted and disheartened by its erratic commander in chief.

Former Foreign Minister Tzipi Livni, an opposition member of Israel’s parliament, laid this out in the starkest possible way.

In a radio interview Wednesday morning, she said “We need the United States to resume its customary leadership role in the international community, and act on Syria.”

Without that, Israelis fear Trump is emboldening their foes.

“There’s a lot of confusion in Israel about Trump’s stance,” says Michael Horowitz, a senior analyst specializing in Israel and Syria at Bahrain’s Le Beck Institute. “The Israelis are puzzled by the American strategy in Syria and concerned there’s no real commitment to roll back Iranian influence in Syria.”

The attack on Iranian forces at Syria’s T4 airbase at the beginning of the week is taken as a clear signal that Israel will act on its own. But the Israelis are under no illusion that such actions can be carried out with impunity.

Speaking in Damascus one day after the airstrike, Ali Akbar Velayati, a former Iranian foreign minister and senior diplomatic adviser to Khamenei, issued a direct threat to Israel. Asked by Iranian state media about “crimes committed by the Zionists against the Syrian forces and defenders of the holy shrines in the Al Tifour Airport,” an alternate name for the T4 base, he said “The crimes will not remain unanswered. Victory is near.”

Russia also slammed Israel. Foreign Minister Sergei Lavrov denounced the raid as “a dangerous development” and the ministry later condemned for good measure what it called Israel’s “discriminatory and unacceptable” attitude toward Palestinians, adding that Israel “used indiscriminate force against civilians.”

The Russian threat of diplomatic moves against Israel was not lost on the Netanyahu government. Neither was the silence of Israel’s traditional allies, principally the United States, about the growing danger Iran poses to Israel.

Israel is taking the Iranian threat very seriously. Israeli media reports that the northern border has been put on high alert, in the event of revenge attacks carried out by Iran or its Lebanese-based proxy militia, Hezbollah, as well the possibility of fallout from a possible U.S. strike against Assad’s forces. Israeli army spokesman Lt. Col. Jonathan Conricus declined to comment on media reports, but said “we are observing and tracking matters, and we are ready.”

Israel’s foreign ministry declined to comment on security arrangements at its embassies around the world, but history indicates Israel should be worried. Iran is implicated in numerous attacks against Israeli installations, from the bombing of its Buenos Aires embassy in 1992 to an attempt on the life of its diplomats in Bangkok in 2012. A 2012 attack that left five Israelis dead in Bulgaria is similarly blamed on Iran.

On Tuesday, the hosts of a popular drive-time radio show opened with the jitters, “So? Are we expecting a terror attack? Where?”

Interviewed on the same program, Justice Minister Ayelet Shaked returned to what is fast becoming Israel’s mantra: the emergent realization that the world may not share its apprehension about Iranian entrenchment along its northern frontier.

“I hope the international community will join our efforts not to allow Iran a permanent presence on our border,” she said, “but if the international community does not, we’ll act to prevent this on our own.”

One of the most critical issues is the concern that Iran will succeed in establishing an open road from Iran through Iraq and Syria to Lebanon, with the ability to arm and deploy major offensive forces. Right now, as Trump has been informed many times, the relatively small U.S. presence in Syria, working with local allies, prevents that. But the allies can be as fickle as the Americans, and the whole thing could crumble after a pullout.

For Israel, says Ehud Yaari, an Israel-based fellow at the Washington Institute for Near East Policy “the central question is ‘Will Trump remove the 2,000 U.S. troops stationed along the Euphrates [River in Syria]?’ Together with some 45,000 Kurdish and Syrian Democratic Forces, they control about one-fourth of Syria and they are the only thing preventing Iran from carving out the land corridor it desires.”