The parallel with Vietnam is very strained. The US and Vietnam are not inherent enemies. They had no deep-seated grievance. The US went to war with no strategic rationale for what we were doing beyond a weak domino theory. The far more important insight, that a strong Vietnam is a great counter to Chinese expansion, should have led the US to support any popular Vietnamese national government.
In contrast the US and the mullahs who rule Iran are bitter enemies and the US has a major strategic interest in making sure a hostile power cannot attain hegemony and cut off the flow of oil from the MidEast. Here are some key points:
- The Iranian mullahs have a deep hatred for the US. They are not our friends. Taking US diplomats hostage is one of the foundational acts of their regime. Chanting “Death to the US” is tops on their hit parade.
- The Iranian mullahs want to take over the world and compel everyone to accept their Shia brand of Islam. They view themselves as fighters and heirs to a 1300 year long struggle against the Sunnis. You cannot give them Sudetenland and have any realistic expectation that will be the end of it.
- The Iranian regime is aggressive and expansionist. It is fielding armies, supplying arms, and sponsoring terror in many places, from Syria to Yemen to Lebanon to Gaza. It is behind numerous terror attacks in Europe.
- The Iranian regime is repressive. It brutally repressed the Green Movement in 2009, and killed food and democracy protestors last year. It has fashion police who beat women who aren’t adequately covered up in public. It executes gays. Democracy is allowed but only within the narrow confines of regime- approved choices.
- The regime has a lot of internal opposition. It is rightfully paranoid that people are plotting its overthrow. There is much pro-US and pro-West sentiment kept under wraps. Older people wanted to get rid of the Shah and move to a tolerant government, not an authoritarian dictatorship. There is still a sense among many that the revolution was stolen.
The immediate situation is far more troubling than you describe it. Iran has been making it clear it has no intention of getting out of Syria. The drawdown of US troops in Syria did not lead to a commensurate reduction by the Iranians Revolutionary Guard or Iranian regulars. The US declared the RG a terrorist group. Meanwhile the Iranians are stocking Hezbollah with thousands of missiles and periodically having it provoke Israel across Lebanese armistice lines. Most serious in terms of carnage, the Iranians are helping the Houthi rebellion in Yemen. The Saudis have bombed the hell out of the place, but will be unlikely to achieve a victory as long as Iran supplies the Houthis.
Most recently, as the US ended waivers on trade sanctions against Iran, 4 ships were attacked in the Persian Gulf.
Saudi Arabia convened a summit of Arab nations to discuss what to do. It is not clear if Iran is the culprit behind the attacks but everyone thinks so. The US military deployments are a way of saying to the ayatollah, “don’t increase the level of violence and confrontation with Suadi Arabia and Israel and above all don’t even think about blowing up oil tankers or impeding the flow of oil through the straits” The deployments are a way of deterring Iran from attacks on Israel and Saudi Arabia as well as on US forces in the region. At this stage it doesn’t look like Vietnam.