There are sharp divisions in the Administration over how to respond to Iran at a time when tensions are rising about Iran's nuclear policy and its intentions in the Middle East.
Some senior US officials said the plans, even at a very preliminary stage, show how dangerous the threat from Iran has become. Others, who are urging a diplomatic resolution to the current tensions, said it amounts to a scare tactic to warn Iran against new aggressions.
European allies who met Secretary of State Mike Pompeo today said that they worry that tensions between Washington and Tehran could boil over, possibly inadvertently.
More than a half-dozen US national security officials who have been briefed on details of the updated plans agreed to discuss them with the New York Times on the condition of anonymity. Spokesmen for Shanahan and General Joseph Dunford, the chairman of the Joint Chiefs of Staff, declined to comment.
The size of the force involved has shocked some who have been briefed on them. The 120,000 troops would approach the size of the US force that invaded Iraq in 2003.
Deploying such a robust air, land and naval force would give Tehran more targets to strike, and potentially more reason to do so, risking entangling the US in a drawn out conflict. It also would reverse years of retrenching by the US military in the Middle East that began with President Barack Obama's withdrawal of troops from Iraq in 2011.
But two of the US national security officials said Trump's announced drawdown in December of American forces in Syria, and the diminished naval presence in the region, appear to have emboldened some leaders in Tehran and convinced the Islamic Revolutionary Guards Corps that the US has no appetite for a fight with Iran.
Several oil tankers were attacked or sabotaged off the coast of the United Arab Emirates over the weekend, raising fears that shipping lanes in the Gulf could become flashpoints. "It's going to be a bad problem for Iran if something happens," Trump said, asked about the episode.
Emirati officials are investigating the apparent sabotage, and US officials suspect that Iran was involved. Several officials cautioned, however, that there is not yet any definitive evidence linking Iran or its proxies to the attacks. An Iranian Foreign Ministry spokesman called it a "regretful incident," according to a state news agency.
The high-level review of the Pentagon's plans was presented during a meeting about broader Iran policy. It was held days after what the Trump Administration described, without evidence, as new intelligence indicating that Iran was mobilising proxy groups in Iraq and Syria to attack US forces.
As a precaution, the Pentagon has moved an aircraft carrier, B-52 bombers, a Patriot missile interceptor battery and more naval firepower to the Gulf region.
At last week's meeting, Shanahan gave an overview of the Pentagon's planning, then turned to Dunford to detail various force options, officials said. The uppermost option called for deploying 120,000 troops, which would take weeks or months to complete.
Among those attending the meeting were Shanahan; Bolton; Dunford; Gina Haspel, the CIA director; and Dan Coats, the director of national intelligence.
As recently as late April, a US intelligence analysis indicated that Iran had no short-term desire to provoke a conflict. But new intelligence reports, including intercepts, imagery and other information, have since indicated that Iran was building up its proxy forces' readiness to fight and was preparing them to attack US forces in the region.
The new intelligence reports surfaced on the afternoon of May 3, Shanahan told Congress last week. On May 5, Bolton announced the first of new deployments to the Gulf, including bombers and an aircraft carrier.
It is not clear to US intelligence officials what changed Iran's posture. But intelligence and Defence Department officials said American sanctions have been working better than originally expected, proving far more crippling to the Iranian economy — especially after a clampdown on all oil exports that was announced last month.
Part of the updated planning appears to focus on what military action the US might take if Iran resumes its nuclear fuel production, which has been frozen under the 2015 agreement. It would be difficult for the Trump Administration to make a case that the US was under imminent nuclear peril; Iran shipped 97 per cent of its fuel out of the country in 2016, and currently does not have enough to make a bomb.
That could change if Iran resumes enriching uranium. But it would take a year or more to build up a significant quantity of material, and longer to fashion it into a weapon. That would allow, at least in theory, plenty of time for the US to develop a response — like a further cutoff of oil revenues, covert action or military strikes.
The previous version of the Pentagon's war plan included a classified subset code-named Nitro Zeus, a cyberoperation that called for unplugging Iran's major cities, its power grid and its military.
The idea was to use cyberweapons to paralyse Iran in the opening hours of any conflict, in hopes that it would obviate the need to drop any bombs or conduct a traditional attack. That plan required extensive presence inside Iran's networks — called "implants" or "beacons" — that would pave the way for injecting destabilising malware into Iranian systems.
Two officials said those plans have been constantly updated in recent years.
But even a cyberattack, without dropping bombs, carries significant risk. Iran has built up a major corps of its own, one that successfully attacked financial markets in 2012, a casino in Las Vegas and a range of military targets. US intelligence officials told Congress in January that Iranian hackers are now considered sophisticated operators who are increasingly capable of striking US targets.
Written by: Eric Schmitt and Julian E. Barnes
© 2019 THE NEW YORK TIMES