I can't say it's much of a surprise that U.S. special forces operators are assisting the Saudis in their war against Iranian-backed Houthi rebels in Yemen.  Our special forces carry out missions in many places that the public is kept in the dark about.

But the significance is, when viewed in the context of what else is happening in the Middle East, that Iran is being checked on several fronts by a coalition of U.S., Saudi, and Israeli military forces.

AFP:

According to the Times, which cited US officials and European diplomats, the Army special operations soldiers arrived in December to help Saudi counterparts locate launch sites and destroy the Huthis' missile supplies.

The unannounced move shows a deepening US involvement in Yemen's war that has seen the country spiral toward famine and claimed almost 10,000 lives.

Citing operational security, the Pentagon said it could not comment on the makeup of forward-deployed forces.

The Pentagon's "limited non-combat support, such as intelligence sharing, focuses on assisting our partners in securing their borders from cross-border attacks from the Huthis," military spokesman Major Adrian Rankine-Galloway said.

The Times said there was no indication the commandos had crossed into Yemen.

Saudi Arabia has since March 2015 led a US-backed coalition of Arab states fighting to roll back the Huthis in Yemen and restore its neighbor's internationally recognized government to power.

Officials told the Times the US troops are training Saudi forces to secure the border.

The Iranians deny they're assisting the rebels, but arms shipments from Iran have been detected via Oman, and someone is training the Houthis to use the sophisticated missiles they are using against the Saudis.  The Iranian Revolutionary Guards are thought to be heavily involved in the Yemen civil war, and their support for the Houthis has been significant.

Does U.S. assistance to the Saudis risk involving Americans in another useless Middle East war?  The Saudis have some of the most sophisticated and technologically advanced weapons in the Arab world thanks to U.S. arms sales.  But like most Arab armies, they lack training.  The Saudis are helping contain Iranian ambitions by denying the Houthis a victory in Yemen.  In the context of the broader Middle East, with Israel attacking Iranian targets in Syria and Hezb'allah targets on the border with Lebanon, an anti-Iranian military coalition is emerging.

This will prove useful if, as expected, Donald Trump pulls out of the Iran nuclear deal and the Iranians ramp up their nuclear program.  At that point, all options for action against Iran would be on the table, and Tehran would be facing a most formidable military coalition.