While Russian and Iranian-backed Bashar al-Assad's regime is consolidating its grip on most areas once controlled by various rebel groups in Syria, Iran's involvement and military footprints in the country have some experts and U.S. lawmakers concerned that Tehran might be in the process of establishing long-term presence in Syria in an effort to project regional power in the long term.
"These countries [Russia and Iran] are digging into Syria preparing for the long haul, and the implications for the U.S. interests and those of our partners are still coming into focus," Republican Ileana Ros-Lehtinen of Florida, Chairman of the House Committee on Foreign Affairs, said during a recent congressional hearing on U.S policy in Syria.
Lehtinen added that U.S. needs a "coherent" and "comprehensive" strategy to prevent Iran's growing influence in the region.
"After signing a deal for additional military cooperation with Assad last month, Iran is showing no signs of leaving Syria anytime soon. The U.S. needs a comprehensive and coherent strategy for Syria that rolls back Iranian influence in the Middle East," she said.
Some analysts such as Majid Rafizadeh, president of International American Council on the Middle East, echo Lehtinen's concerns and call for measures to stop Iran's encroachment in Syria and the region.
"Iran is solidifying its presence in Syria in three different approaches: militarily, economically and politically. Tehran is sealing long-term deals and agreements with the weak Syrian state to 'reconstruct the Syrian military industry,'" Rafizadeh told VOA.
"This will give the IRGC [Islamic Revolutionary Guard Corp], the Quds Force and Iran's intelligence the perfect excuse to remain in Syria, set up more military bases, and further infiltrate Syria's security apparatuses," Rafizadeh added.
Iran's engagement in Syria began gradually since the start of the country's civil war in 2011, initially in the form of providing military advisers to the Syrian regime. The engagement later morphed into a full-scale military intervention where the regime sent its forces and employed its proxies to fight alongside Assad to crack down on the various Syrian rebel groups in the country.
Last August, Amir Hatami, Iran's minister of defense, made a two-day visit to Syria to meet with Assad. During the visit, Hatami agreed to a defense cooperation agreement with his Syrian counterpart, Ali Abdullah Ayoub.
Following Hatami's visit, Iran's military attache in Damascus, Abolghasem Alinejad, was quoted by an Iranian state news agency that Iranian advisers would remain in Syria indefinitely.
"The continued presence of Iran's advisers in Syria is one of the areas covered in the defensive-technical agreement between Tehran and Damascus," Alinejad told Islamic Republic News Agency (IRNA) last year.
Iran reportedly has been spending billions of dollars in the Middle East to gain influence and prop up regimes.
According to a report published by the U.S. Department of State earlier this month, Iran has spent about $16 billion to destabilize the Middle East by funding proxies in different countries including Yemen, Iraq and Syria.
"Since 2012, Iran has spent over $16 billion propping up the Assad regime and supporting its other partners and proxies in Syria, Iraq, and Yemen," the report said.
Sunni Shi'ite dynamics
Some experts are also charging that Tehran is trying to take advantage of the demographic changes and displacements of people in Syria by seeking to increase the dominance of the country's Shi'ites at the expense of marginalizing Sunnis.
"Iran brought the families of its [Shi'ite] militias from Pakistan, Afghanistan and Iraq to live in the properties that used to belong to the Sunni communities before displacing the Sunnis to other areas. Iran was also behind issuing decree No. 10 in Syria," Hanin Ghaddar, an expert at the Washington Institute for Near East Policy, told VOA.
Ghaddar was referring to what is known as Law No. 10 in Syria, which is a decree, issued by the Syrian president in April to plan the reconstruction of areas destroyed by war.
The law seizes the properties of displaced Syrians unless they prove the ownership of their properties in 30 days, which many analysts say is almost impossible because of the scale of the destruction and the fear of potential persecution by the Syrian regime.
U.S. officials repeatedly urged Iran to remove its forces from Syria, but Iranian officials maintain that their presence in the country is legitimate under the request of the government in Damascus.
Last week, U.S. Secretary of State Mike Pompeo warned that Syria will not receive U.S aid for reconstruction if Iran continues to have troops inside the country.
"If Syria doesn't ensure the total withdrawal of Iranian-backed troops, it will not receive one single dollar from the United States for reconstruction," Pompeo said in his keynote address at the Jewish Institute for National Security of America, a pro-Israel group.
Pompeo also said the U.S. would focus on initiating a peaceful political process and the removal of all Iranian troops and proxies from Syria.
But some analysts charge that Iran's total exit from Syria might take time, but there are steps that could be taken to contain Iran's influence.
"There can be many steps taken to contain Iran at this point. The demographic changes need to be countered, the refugees return, containing Hezbollah in Lebanon, working with local allies, working with local tribes, cutting the land bridge," Ghaddar, of the Washington Institute, said.
Ghaddar believes that a political change in Syria will also be an effective tool to limit Iran's presence in Syria.
"A political change in Syria will limit Iran's presence depending on what kind of political change we are talking about," Ghaddar said.
"If we are talking about transitional period where Assad regime goes, which does not seem like it at this point, and we look at a new power, new people and a new elections then, yes, this will contain Iran's power in Syria because at the end of the day they are considered a foreign legion," she added.