U.S. Secretary of State Rex Tillerson has told his counterparts at NATO that the United States is committed to Ukraine's territorial integrity and that U.S. sanctions against Russia will remain in place "until Moscow reverses the actions that triggered our sanctions."
Tillerson was attending his first meeting of NATO foreign ministers amid widespread doubts about the U.S. commitment to the alliance and worries about U.S. President Donald Trump's stated desire for closer relations with Moscow.
"We understand that a threat against one of us is a threat against all of us, and we will respond accordingly," Tillerson said. "We will uphold the agreements we have made to defend our allies."
He was equally emphatic regarding Ukraine.
"We do not and will not accept Russian efforts to change the borders of the territory of Ukraine," he said.
He added that "the United States sanctions will remain in place until Moscow reverses the actions that triggered our sanctions."
Western states have imposed sanctions against Moscow for its illegal 2014 annexation of Ukraine’s Crimea region and for Russia’s support of separatist fighters in eastern Ukraine.
Russia has said it will not even discuss the status of Crimea and has denied that it is providing military support to the militants in eastern Ukraine, despite compelling evidence to the contrary.
The U.S. top diplomat said Washington "will continue to hold Russia accountable to its Minsk commitments," referring to the Minsk process to resolve the Ukraine crisis.
He called on Russia to push the separatists to end the violence and to allow monitors from the Organization for Security and Cooperation in Europe complete access to the conflict zone.
Speaking to journalists before the Brussels talks, NATO Secretary-General Jens Stoltenberg described ties between European members and the United States as "rock solid" and said the alliance has "a united position on Russia: strong defense and deterrence combined with dialogue."
Ukrainian Foreign Minister Pavlo Klimkin joined his NATO counterparts in the afternoon for a session of the NATO-Ukraine Commission, which Stoltenberg described as "a strong sign of our continued commitment" to the country.
After a session of the Russia-NATO Council on March 30, Stoltenberg told journalists that NATO was firm in its support for Ukraine's sovereignty and territorial integrity.
"The allies do not and will not recognize Russia's illegal annexation of [the Ukrainian region of] Crimea," Stoltenberg said.
Russia's ambassador to NATO, Aleksandr Grushko, in turn criticized NATO for "continuing to provide political and practical support to Kyiv," a policy that he said is "at odds with genuine interests of conflict settlement."
WATCH: NATO Affirms Commitment To Balkans, Ukraine Security Support
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NATO Affirms Commitment To Balkans, Ukraine Security Support
Tillerson To Allies: Boost Spending
As widely expected, Tillerson also urged NATO allies to boost defense spending or come up with plans to reach the alliance's budget targets.
Washington is spending a "disproportionate share" on defense compared with its partners, Tillerson said.
NATO members pledged in 2014 to move toward a guideline of spending 2 percent of gross domestic product (GDP) on defense within a decade, but only the United States and four other NATO members -- Estonia, Greece, Poland, and Britain -- currently meet the target.
"Our goal should be to agree at the May leaders meeting that by the end of the year all allies will have either met the pledge guidelines or will have developed plans that clearly articulate how...the pledge will be fulfilled," Tillerson said.
After the meeting, German Foreign Minister Sigmar Gabriel seemed to reject Tillerson's demand to meet the target.
"Two percent would mean military expenses of some 70 billion euros," Gabriel said. "I don't know any German politician who would claim that is reachable or desirable."
The Brussels meeting was the first NATO meeting to be attended by Tillerson.
The meeting was initially scheduled for next week and Tillerson had planned to skip it, citing other commitments, but it was subsequently rescheduled.
The gathering is preparation for a May 25 NATO summit, which U.S. President Donald Trump has said he will attend.