Russian Foreign Minister Sergey Lavrov said on Friday that Russia, Iran and Syria have insisted that the U.S. and its allies must respect Syria’s sovereignty in line with international obligations.

“We will insist on the strict fulfillment by all without exception of those obligations set forth in the UN Security Council resolution, including full respect for the sovereignty and territorial integrity of the Syrian Arab Republic,” Sputnik quoted Lavrov as saying in a joint press conference with Mohammad Javad Zarif and Walid Muallem, the Iranian and Syrian foreign ministers, in Moscow.

Lavrov said that actions such as the U.S. airstrike on Syrian province of Idlib on April 7 to change the Syria regime would fail.

Those who are trying to block the proposal of Russia and Iran on the establishment of an independent commission to investigate the chemical attack on Idlib have something to hide, Lavrov said.

The Syrian foreign minister called the trilateral meeting with Lavrov and Zarif a ‘strong message’ after the U.S. strike against Syria.

Muallem said that there is no justification for the U.S. missile attack.

“We shall facilitate everything which will lead to the success of the commission’s work on investigation. Our question is as follows, why are the United States and its allies afraid of such commission being established? If the U.S. strike has no justification, it is blatant aggression against Syria’s sovereignty,” the Syrian foreign minister pointed out.

The Iranian foreign minister agreed with his Russian and Syrian counterparts on the need to boost cooperation in fighting terror, as well as carrying out the chemical attack probe.

“The use of chemical weapons as a pretext for taking actions against the sovereignty and territorial integrity of an independent state and a UN member is very dangerous. The international investigation is required in this case… It is necessary to prevent such actions in the future,” Zarif asserted.

Zarif added, “We shall increase the level of cooperation on the international level. The first track is the investigation of this act, of this incident … The second, international cooperation on fighting terrorism and extremism … The third direction is restoration of the political plan.”

A suspected chemical attack in the northern Syrian province of Idlib on April 4 left at least 80 people killed and hundreds injured.

On April 7, the U.S. launched cruise missiles at Syria’s Shayrat airfield from which President Donald Trump claimed a chemical weapons attack had been launched.