Iran and Syria on Monday signed a deal for military cooperation, Iran's Tasnim news agency reported, but did not provide any details about the deal.
On Sunday, Iranian Defense Minister Amir Hatami said his country will continue its support of the Syrian government to ensure improved security in the region, and that the nature of the two countries' cooperation would not be decided by a "third party."
The remarks come as Israel repeatedly voices concern over Iran's growing influence in Syria, accusing Iran of seeking to establish a military foothold in Syria, which shares a border with Israel.
The United States has also been pressing for Iran to withdraw its fighters from Syria. U.S. National Security Adviser John Bolton said recently that the topic was discussed in recent meetings between U.S. President Donald Trump and Russian officials, and that Russian President Vladimir Putin has expressed his support for removing Iran from Syria. Bolton said the issue was a U.S priority.
Iran says its presence in Syria is at the invitation of the Syrian government.
"No third party can affect the presence of Iranian advisers in Syria," Hatami told reporters in Damascus on Sunday.
His comments came at the start of a two-day visit to Syria, where he met with Syrian President Bashar Assad and other senior officials. The high-level military delegation headed by Hatami is expected to boost cooperation between the two countries, and Iranian media reported that the two are expected to sign new military and defense agreements.
Iran has provided key support to Assad in the seven-year civil war, sending thousands of military advisers and allied militiamen to bolster Assad's forces.
Hatami said he hoped Iran can play a "productive role" in Syria's reconstruction, Iran's Press TV reported.
"Iran will spare no effort to maintain Syria's territorial integrity, because security in the country will help regional stability," Hatami said in a meeting with his Syrian counterpart General Ali Abdullah Ayyoub in Damascus.
He met later with Assad.
Earlier this year, Israeli jets carried out a number of strikes against suspected Iranian bases in Syria, including an unprecedented bombardment of Iranian military installations in May, reportedly in retaliation for an Iranian rocket barrage on Israeli positions in the Golan Heights.
Hatami's two-day visit comes as Syria gears up for an expected offensive in the northern Idlib province, the last major rebel stronghold, which also houses a large al-Qaida presence. The province is home to nearly 3 million people and borders Turkey, which fears an offensive may trigger a humanitarian and security catastrophe.
Ayyoub said the Syrian government is determined to restore government control over Idlib whether through reconciliation deals or with military operations.
A Turkish, Russian and Iranian summit is expected in early September in Tehran to discuss Syria.
Meanwhile, the situation in Idlib topped the agenda during talks between Turkish Foreign Minister Mevlut Cavusoglu and his Russian counterpart Sergey Lavrov in Moscow on Friday. Turkey has sought to delay any offensive, while Russia has expressed growing impatience, accusing insurgents of targeting its forces from the province.