Russian Foreign Minister Sergey Lavrov admonished Secretary of State Rex Tillerson on Tuesday for the Trump administration’s “aggressive” remarks on North Korea.

Lavrov denounced “Washington’s aggressive rhetoric” during a phone call with Tillerson, Reuters reported, citing the Russian foreign ministry.

The Russian diplomat said U.S. rhetoric had heightened tensions in the region and called it unacceptable, according to Reuters.

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During their call, the two diplomats also reportedly discussed possible paths forward regarding the conflict in Syria and the situation in Ukraine.

The phone call comes after Reuters reported that Russia said it would mediate talks between the United States and North Korea should the two countries accept its offer and be willing to come to the negotiating table.

Lavrov on Monday stressed the point, calling for the two nations to start negotiations while underscoring the Kremlin’s readiness to serve as a facilitator of the meeting.

The offer comes amid escalating tensions between Washington and Pyongyang with both countries intensifying their rhetoric this year.

President Trump warned in a roll out of his national security strategy earlier this month that the U.S. is ready to respond to threats from North Korea with “overwhelming force.” He previously warned of “fire and fury” should North Korea continue threatening the U.S.

Tillerson and Trump have given mixed messages regarding the administration’s stance toward North Korea after Pyongyang launched an intercontinental ballistic missile late last month.

While Tillerson voiced support for opening diplomatic dialogue between the two states, Trump said he would not take part in any talks with Pyongyang unless the isolated state agreed to give up its pursuit of nuclear weapons.

Despite a series of sanctions imposed against North Korea for its weapons program, the country has continued to pursue its nuclear and missile programs.

The United Nations Security Council on Friday unanimously voted to slap harsher sanctions on North Korea in response to its latest intercontinental ballistic missile test.