The Kremlin on Monday said it “deeply regrets” U.S. airstrikes on Iran‘s nuclear facilities over the weekend, adding that it had not been informed in advance and expressing support for Tehran.

Russian President Vladimir Putin called the strikes an “unprovoked aggression that has no justification” in his first public remarks on the incident, delivered during talks with Iranian foreign Minister Abbas Araghchi.

“We, of course, condemn the growing number of participants in this conflict and the renewed escalation of tensions in the region, and we express deep regret in this regard,” Kremlin spokesman Dmitry Peskov told reporters.

Neither Putin nor Peskov explicitly named the United States in their comments.

Peskov referred too the Russian Foreign Ministry’s earlier statement on Sunday, which strongly condemned the strikes as “irresponsible” and a “gross violation of international law” that could destabilize both regional and global security.

He added that, while Putin and U.S. President Donald Trump had discussed Iran’s nuclear program in recent phone calls, Washington had not provided Moscow with “detailed data” about its planned operation.

His remarks followed a Reuters report citing unnamed Iranian officials who said Tehran had been “unimpressed” with Moscow’s support and was seeking further backing in its standoff with the U.S. and Israel.

Araghchi met with Putin on Monday and was expected to deliver a letter from Supreme Leader Ayatollah Ali Khamenei requesting Russia’s support,according to the report.

peskov said Russia’s offer to mediate, along with its condemnation of the U.S. strikes, amounted to “a form of support” for Iran, adding that any additional assistance would “depend on what iran needs.”

Reuters did not specify what kind of support Iran was seeking from Moscow.