Jim Michaels

USA TODAY

Defense Secretary Jim Mattis said Thursday that the United States is “not in a position right now” to forge military ties with Russia, which still needs to abide by international norms.

“The point about Russia is that they have to live by international law just like we expect all mature nations on this planet to do,” Mattis said in Brussels, where he met with his NATO counterparts.

Mattis said political leaders will engage with Russia in an effort “to find common ground or a way forward where Russia, living up to its commitments, will return to a partnership of sorts here with NATO.”

“But Russia is going to have to prove itself first and live up the commitments they have made in the Russia-NATO agreement,” he said.

Russia and NATO have agreed to work together in the past, but Russia’s annexation of Crimea and support for separatists in eastern Ukraine have strained relations with the alliance.

President Trump, during his election campaign, raised the possibility of U.S. cooperation with Russia to defeat the Islamic State in Syria.

The Pentagon in the past has accused Russia of limiting its military campaign in Syria to supporting the regime of President Bashar Assad and not focusing its attacks on the Islamic State. The U.S. military has been wary of cooperation for that reason and because Russian bombing is often indiscriminate, hitting schools, mosques and hospitals.

The U.S. and Russia exchange information about where their aircraft are operating in order to avoid mishaps. But the two sides do not cooperate or coordinate airstrikes in Syria.

Also Thursday, Marine Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, met with his Russian counterpart, Gen. Valery Gerasimov, in the former Soviet republic of Azerbaijan.

"The military leaders exchanged their views on the state of U.S.-Russian military relations and of the international security situation in Europe, the Middle East, and other key regions," Dunford's office said in a statement.

Mattis made the remarks about Russia a day after he warned NATO allies that they must fulfill their military funding obligations or the United States would “moderate” its own support for the alliance.

Mattis urged NATO allies to approve a measure that provides deadlines for member countries to reach a spending goal of 2% of its gross domestic product on defense.

“Americans cannot care more for your children’s future security than you do,” Mattis said.

On Thursday, Mattis said his remarks were well received by United States' NATO allies, and he doesn’t anticipate ever having to lessen the nation's commitment to the alliance.

“Sometimes you say the things you don’t want to have happen so that you head them off,” Mattis said.