DUBAI and BRUSSELS — As the United States receives commitments from Gulf Arab allies to contribute more to a coalition campaign in Syria, doubts remain because of their ongoing military involvement in Yemen.

Furthermore, statements by unnamed Saudi officials earlier this month about a force of 150,000 — including troops from Gulf Cooperation Council (GCC) partners Sudan, Egypt and Jordan — being prepared to invade Syria from Turkey have been rebuffed by at least two members of the anti-Islamic State coalition.

A Jordanian official confirmed that the country will not participate in any Turkish- or Arab-led Syrian invasion unless mandated by the United Nations, led by western forces and coordinated with Russia.

"Jordan is not going to send ground forces into Syria unless these troops are led by Americans and British," the Jordanian official said, speaking on condition of anonymity. "We have very long borders with Iraq and Syria which are more than 550 kilometers. Any ground troops including Jordanian forces should be sent after a UN approval and after full coordination with Russia."

On Feb. 9, a senior Kuwaiti official told Reuters that despite Kuwait's backing of international efforts against hard-line Islamist groups, the Gulf Arab state's constitution prevents it from fighting in anything but defensive wars.

"Kuwait stands shoulder-to-shoulder with our brothers in Saudi on all fronts. We are always ready and able to provide what is needed to our Gulf partners within the confines of our constitution," Sheikh Mohammad al-Mubarak Al-Sabah, Kuwait's minister for cabinet affairs, told Reuters in Dubai.

He indicated that support to operations could be limited to only intelligence-sharing and the provision of establishments required by the coalition to facilitate their activities.

With respect to ground operations, US Defense Secretary Ash Carter said Feb. 11 in Brussels that a variety of options have been discussed with Arab partners.

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"First of all, there is training of both military forces and police forces. We need forces on the ground that participate in training. Then enabling, including even accompanying partner forces. That's something that ground forces can do. We obviously talked about, but I'm not going to talk about it here, special forces that have some very special and distinctive capabilities," he said.

"We also talked about logistics support, sustainment, rebuilding of a kind that is going to have to go on Ramadi. So all of these are activities that coalition partners, to include Saudi Arabia, will participate in, and that whole gamut we discussed today, both in my individual meeting with the defense minister and deputy crown prince and also at the larger meeting where we were all together, the whole raft," he added.

Members of Saudi Special Forces show their skills during their graduation ceremony in the capital Riyadh, on May 19, 2015. AFP PHOTO / FAYEZ NURELDINE (Photo credit should read FAYEZ NURELDINE/AFP/Getty Images)

Saudi Special Forces demonstrate their skills during a May graduation ceremony in Riyadh.

Photo Credit: Fayez Nureldine/AFP via Getty

On the Saudi capability to wage a two-front war in both Syria and Yemen, Carter said he does not think they wish to be doing that any more than anybody else would wish, but they do have the capability and willingness to put the resources into the anti-ISIS fight.

"At the same time I can't speak for them, but certainly we wish on their regard and we wish on everybody's regard in Yemen that things would wind down there because it's not good for the population of Yemen, and that situation needs to be settled so that people aren't fighting there," he said.

According to Oubai Shabandar, a former US Department of Defense official and principal at Dubai-based advisory Dragoman Partners, the Saudi presence in Syria depends on their scope of participation.

"The Saudis have developed an exceptional projection capability especially with their air transport and their special forces that they have developed in the past few years," he said. "Their ability is to move in quickly and establish local partnerships. Its modeled after the American approach. They are elite units. They are fast and mobile and with a full-spectrum capability to move and operate on short notice.

"That said, absolutely the Saudis have the capability to project to southern Turkey pretty quickly but with units that have specific function."

However Syria is a different animal given the geopolitical complexities, the Russian involvement and the Iranian presence on the ground in northern Syria, Shabander said.

"A full-fledged Turkish-Arab conventional force incursion into northern Syria requires either a NATO air umbrella or international coalition support," he said.

On the involvement of Saudi forces in Yemen, Shabandar said that the Arab coalition understands it's going to be a resource-intensive effort that presents challenges to simultaneously project in other fronts at the same level.

"But it can absolutely be done as long as it is a truly joint effort with international strategic partners," he said.

"The logistical challenge doesn't preclude sending expeditionary and recon elements into the Syrian-Jordanian border or Syrian-Turkish border with Turkish or Jordanian forces but the wild factor at the end of the day is: Will NATO and/or the United States provide the needed air cover to successfully accomplish a stabilization mission against Daesh in northern and southern Syria?" he said, using an alternative name for the Islamic State group. "Let's not forget that the ongoing Russian aerial bombardment is per military reports actually enabling Daesh in northern Syria and Damascus suburbs"

He added that Shia extremist foreign fighters that are being flown into Syria would view an Arab coalition effort into northern Syria as a direct threat because the Shia extremist forces that are fighting on the Aleppo front are direct clients of the Iranian Revolutionary Guard, so essentially they are of the same strain as the Houthi forces in Yemen.

The Saudi military presence in Yemen is predominantly focused on the protection of their southern border, said Gulf security and military expert Matthew Hedges.

"Overlooking Saudi Arabian National Guard, the Saudi Armed Forces are currently operating from bases within the kingdom with the Air Defense Command, the busiest of the divisions," he said.

Saudi Arabia will most likely deploy special operators, combat aircraft and some combat troops; however, it is unlikely they will dedicate more than 3,500 combat troops and 6,500 support personnel — equivalent to the number operating in Yemen, Hedges said.

"The quality of manpower in either the Yemen or Syria theater will be greatly affected by this decision. With only partial, previous combat experience, it is unlikely there will be enough troops ready and capable of contributing to both theaters. This has led to the suggestion that Saudi Arabia to enter a ground war in Syria is to prompt an international coalition to form to counter Islamic extremism and a resurgent Assad regime," he added.

According to National Defense University professor Paul Sullivan, Saudi Arabia should be careful not to overstretch its military and diplomatic efforts, as Syria could be "quicksand" for them.

"If Saudi Arabia, the UAE and other GCC states do not get involved, a solution to the Syria problem may only a temporary one," he said. "Many think that the solution to ISIS has to come from Muslim soldiers, sailors and airmen. That may have some accuracy to it. Saudi Arabia and the rest of the GCC are facing many threats.