While the Arab coalition has control of the air and can accurately hit targets anywhere in the country, on the ground the government and the coalition do not have enough troops to control all of the country. The Iran backed Shia rebels and some Sunni groups control most of the northwest (to the Saudi border), the capital and key towns and cities that must be fought over and garrisoned before the government can claim more territory. The government and coalition forces have taken some of the Red Sea coast but have not got enough troops to stop the rebels from moving about and continuing to receive weapons and other equipment smuggled in by Iran.
Large areas in the east and south are controlled or, more frequently contested by separatist tribes that will work with AQAP (Al Qaeda in the Arabian Peninsula), especially if the local AQAP faction contains members from that tribe and AQAP pays it way. Because of longstanding popular support for Islamic terrorism in these parts of Yemen as well continued support from wealthy Arabs in the region (including Saudi Arabia) AQAP survives. But it is not thriving. Attacks are still carried out but less frequently. American surveillance and airstrikes are having an effect on AQAP but that does not change the fundamentals; tribal support and cash flow.
The Arab coalition has internal disagreements which limit what the group can do. What all the coalition members share (aside from oil wealth) is fear of Iran. What is going on in Yemen reinforces that fear. Iran has created a serious threat to the Gulf Arabs while spending far less than the half billion dollars a month the Yemen effort is costing the Arab coalition. Iran has only a handful of Iranians in Yemen. Most of what are described as “Iranians” in Yemen are Lebanese (Shia Arabs belonging to Hezbollah). The Iranians have always been able to do a lot more with a lot less and this worries the Arabs more than anything else.
The Shia rebels are now threatening to use their Iranian ballistic missiles to hit the UAE base across the Red Sea in Eritrea. At the very least that causes the Arabs to consider moving one of their few Patriot units to Eretria. One of those units has already been moved to Yemen after a ballistic missile hit a coalition base. The Shia rebels also threaten to attack oil tankers (especially Saudi ones) moving through the Red Sea (to reach the Suez Canal and European customers. If that happens it means more Saudi naval forces must come from the Persian Gulf, where most Saudi warships confront Iran.
While the Yemeni Shia appreciate all this clever support from Shia Iran a growing number of Shia rebels have quietly (so far) expressed concern about the ultimate usefulness of Iranian support. Iran has a long tradition of using and abandoning Arab allies, and treating its own Arab minority with great disdain and cruelty. An indication of this possibility is the loss of their Shia Arab ally former president Saleh. Apparently Saleh calculated that it was time to switch sides (an ancient, but dangerous, tradition in Arabia). Saleh is not definitely lost to the cause, at least not yet. Saleh is the kind of guy who always considers counter offers.
The Yemen government continues to accuse Iran of exercising control over the Yemeni Shia rebels and deliberately (but discreetly) sabotaging peace negotiations that the Shia rebels otherwise appear to find acceptable. Several times recently peace negotiations with the rebels seemed to achieve some real progress only to have the rebels later cancel the deal for no reason other than what appears to be Iranian interference. Iran denies such involvement but then Iranian long denied assisting the Yemeni rebels until the evidence became impossible to deny. Now Iran admits backing the rebels but denies exercising a veto over negotiations between the Yemen government and the Shia rebels.
The United States, which participates in the naval blockade of Yemen, points out that Iran is obviously getting major items smuggled in on a regular basis. The blockade ships have had to deal with naval mines, anti-ship missiles and explosive boat attacks that could all be tracked back to Iran. On land there is evidence Iran has brought in ballistic missiles that are now used because the rebels have exhausted the supply they obtained in 2014-15. Most of those missiles are intercepted (using American made and Saudi operated Patriot missiles) over Saudi Arabia, where fragments of the ballistic missiles can be collected and analyzed. This makes it clear where the missiles came from. Iran has also sent in more, and larger, UAVs for the rebels to use (and increasingly lose do to equipment failure or being shot down). Maintaining the naval blockade and keeping all those Patriot air defense units on constant alert is expensive and all because of Iran is still getting enough missile components smuggled in (and assembled) to maintain the ballistic missile threat.
The one specific rebel (and Iranian) vulnerability is the Red Sea port of Hodeida which currently is the only way for the rebels to accept legitimate imports. Those aid shipments contain a lot of smuggled items. This has been the main port for the delivery of foreign aid for civilians in rebel held areas and, in theory, government controlled areas. The UN has been, without much success, trying to get the rebels to allow the UN to police the port and basically control the smuggling and diversion of foreign aid the rebels have been engaged in. Evidence of rebel theft of foreign aid and depriving civilians of essential supplies is piling up and has become difficult to ignore. But Iran has organized an effective media and diplomatic campaign to divert pressure from Hodeida to the impact of the Arab coalition airstrikes on Yemeni civilians. These casualties are largely the result of the rebels deliberately moving and hiding in the midst of civilians. This does offer a lot of protection but does not make the rebels immune to air attack. Iran would use air power the same way the Arabs do and have when they had the opportunity during the 1980s war with Iraq. It was Iran that began using ballistic missiles against Iraqi cities (which were closer to the border than major Iranian cities were). These tactics are being used once more in Yemen but have been thwarted so far by Arab anti-missile defenses. But the Iranians are much better at manipulating the mass media and UN politics (where the Arabs have spent a lot more money for access and influence over the past few decades) and are demonstrating that and enjoying the pain it is causing the Arabs. .
Iran has had a number of notable failures in Yemen. Arab air defenses (especially against ballistic missiles) have been particularly effective and that is discouraging to Iran. So has the competence of the Gulf Arab Air Forces in carrying out a sustained aerial campaign using modern aircraft. The coalition had over 200 combat (mostly) and support aircraft, including several dozen helicopters (most of them armed). That proved to be untrue because crew killed when aircraft (20 so far) were lost were named, hailed as heroes and their careers were described in detail. Most of the aircraft lost were Saudi (12) followed by the UAE (5) with Morocco, Jordan, Bahrain losing one each. That was roughly in proportion to how many aircraft each coalition member contributed. Thus the aircraft lost were One Typhoon, two F-15s, three F-16s, one Mirage 2000, five AH-64s and four other helicopters plus at least five large UAVs.
After the Saudis the UAE was the largest contributor of aircraft. The UAE sent in about 40 F-16Es (mostly) plus some Mirage 2000s and one aerial refueling aircraft. UAE later sent in more AH-64s and light attack aircraft (armed with Hellfire missiles). The UAE also set up an air base across the Gulf of Aden in Eritrea with at least five Mirage 2000s, three AT-802 light attack aircraft, UH-60 and CH-47 helicopters and several Chinese made CH-4 UAVs (similar to the American Predator). This was mainly to tighten the naval blockade that Iran was sometimes evading to get weapons to the Shia rebels.
What scared the Iranians was the skill levels of the Arab aircrew. These pilots had little or no combat experience but since mid-2014 many of them had been flying combat missions against ISIL (Islamic State in Iraq and the Levant) in Iraq and Syria and the air campaign in Yemen demonstrated these pilots, and their ground support facilities, could handle a “surge” (several sorties a day for weeks) and then thousands of more sorties over more than a year of operations.
The coalition thought they got most of the Yemeni ballistic missiles but it was later found that several had survived but none of those fired at targets in Saudi Arabia (where most were aimed) hit anything because the Saudi Patriot anti-missile capability worked. A ballistic missile hit a coalition base in Yemen during September 2015 and in response the UAE brought in a Patriot battery and other anti-aircraft systems which prevented further losses like that.
Another Iranian loss was the inability to blame the outbreak of cholera on the coalition. Iran claimed the deadly cholera was caused by airstrikes but even the most pro-Iran public health specialists could not get behind that. So far nearly 800,000 people in 22 of 23 provinces has been infected and about 2,200 have died. This began in April when living conditions in Saana declined to the point that there was an outbreak of cholera (that is spread by infected water and food). The disease spread from the capital and intensified. This is all because the rebels have not put a priority on maintaining the quality of the water supply. Iran blames the people fighting the rebels, especially Saudi Arabia. But the main problem is the corruption. Aid groups complain that they have to divert money from buying and importing food to medical supplies in order to deal with the cholera outbreak. Asking donor states (and private foundations or individuals) for more money doesn’t work when the destination is a place like Yemen. Because of the Internet donors can more easily exchange information on the success or failure of their efforts. Yemen most frequently comes up on the losing side because of the rampant corruption and banditry.
October 2, 2017: In the northwest (Hajjah province) a Saudi airstrike near the Saudi border killed five Shia rebel leaders attending a secret meeting that got found out.
October 1, 2017: In the north, near the capital Sanaa an American MQ-9 UAV crashed. The U.S. Air Force said the incident was still being investigated but that it appears the UAV was shot down.
September 29, 2017: The UN has agreed to send a war crimes investigation team to Yemen to try and document accusations that both sides are deliberately using tactics that cause enormous harm to the civilian population. The Arab coalition has resisted this effort, backed by Iran, because the Iran backed Shia rebels have proved better able to keep independent investigations out of their territory and it is easier to hide the efforts to keep food and other aid from hostile civilians than it is to hide the activity of Arab coalition air attacks. The Arab coalition does not trust the UN because the UN officials have proved easy for the rebels to bribe or intimidate. This is a common problem worldwide and the UN would rather not dwell on it.
September 25, 2017: The government blames the Shia rebels for delaying efforts to work out a peace deal. This may be the main reason former president Saleh, a key ally of the rebels, is trying to back out of that alliance.
September 23, 2017: In the northwest another rebel ballistic missile was shot down by Saudi Patriot anti-missile missiles after it crossed the border into Saudi Arabia (Asir province). This ballistic missile appeared to be headed for the city of Khamis Mushait rather than the nearby King Khalid Air Base. In March 2017 there was a similar attack involving four ballistic missiles, at least one of them headed for the air base. The Arabs point to these Iranian ballistic missiles and Iranian UAVs as pretty clear evidence that Iran was still smuggling weapons in. Iran denies everything and when confronted with physical evidence insists that the Yemeni Shia made they stuff locally, obtaining technical help via the Internet.
In the north (Sanaa) an American oil specialist was kidnapped in the capital in a public place. The American had been working for the government owned oil company since the 1980s.
September 15, 2017: In the south (Abyan province) three captured al Qaeda men admitted they had killed a Yemen army colonel (who was an intelligence specialist) in August. That sort of thing was not unusual, but one of the interrogators was a son of the murdered colonel and he promptly (and without permission) shot the three men dead. Apparently there will be no formal punishment of the young officer and this is largely attributed to the circumstances, including that the colonel and his family belong to a very powerful Sunni tribe in the south.
September 14, 2017: In the south (Abyan province) an American UAV used a missile to kill three AQAP Islamic terrorists by destroying their vehicle while it was on a country road.
September 13, 2017: In the south (Abyan province) a Saudi Typhoon fighter suffered some equipment failure during a low altitude support mission and crashed. The pilot was killed.
September 12, 2017: A Roman Catholic priest from India was freed from captivity in Yemen with the help (unspecified) of the Omani government. This all began in March 2016 when a group of ISIL gunmen attacked an old age home in the port of Aden run by an Indian charity. The Islamic terrorists killed 16 people (including four elderly Indian nuns) and kidnapped the Indian priest. AQAP promptly denied any involvement but ISIL said nothing and there were soon rumors that ISIL had the Indian priest. It is unclear who was holding the priest as even the captive priest was unclear what group he was being held by.
September 10, 2017: Off the southern coast a UAE aircraft went down due to equipment failure and the pilots was killed. The aircraft type has not been released yet.
September 9, 2017: In central Yemen (Baida province) American UAVs attacked two targets and killed five AQAP Islamic terrorists.