Afghan President Ashraf Ghani and Iranian President Hassan Rohani have vowed increased cooperation between their predominantly Muslim countries to counter the threat from militant group Islamic State (IS).
Ghani arrived in Tehran on April 19 for a two-day state visit, his first official trip to the neighboring country since taking office in September.
Standing alongside visiting Ghani, Rohani said the current regional instability necessitated the sharing of intelligence.
Ghani said IS presents "a serious danger and different form of terrorism," adding, "People die daily, we face barbarism."
Using a common shorthand term for IS, the Afghan president warned that "without greater cooperation, a macabre phenomenon such as Daesh cannot be contained."
"We have agreed to cooperate further in the fight against terrorism, violence, and extremism in the region, especially in border regions," Rohani said. "We need intelligence sharing and, if necessary, cooperation in operations because the problems that exist are not restricted and gradually spread throughout the region, affecting everyone."
Iran state media reported that Ghani's talks with Iranian leaders would also focus on efforts against drug trafficking and the situation of Afghan refugees in Iran.
The Afghan president is being accompanied on the trip by his foreign minister and minister for oil and mines.
Ghani's trip came a day after a massive suicide bombing in the eastern Afghan city of Jalalabad killed at least 33 people and wounded more than 100 others.
Ghani blamed that attack on IS, which appears to be making inroads in war-ravaged Afghanistan.
During a recent trip to the United States, Ghani warned that IS was "already sending advance guards to southern and western Afghanistan to test for vulnerabilities."