President Trump is set to attend a NATO summit in Brussels in May to “reaffirm” U.S. commitment to the alliance. White House press secretary Sean Spicer confirmed the news late Tuesday, saying Trump “looks forward to meeting with his NATO counterparts to reaffirm our strong commitment to NATO, and to discuss issues critical to the alliance, especially allied responsibility-sharing and NATO’s role in the fight against terrorism.” The announcement follows mounting concerns over U.S. commitment to the alliance, after Trump repeatedly criticized other member states and once described NATO as “obsolete.” On Saturday, he lamented on Twitter that it was “very unfair” to the U.S. that NATO member states were not contributing more to defense, claiming Germany owes “vast sums” of money. Concerns also intensified Monday when Reuters reported that U.S. Secretary of State Rex Tillerson planned to skip a NATO meeting in early April—his first meeting with NATO foreign ministers. Just as the White House announced Trump’s attendance of the NATO summit on Tuesday, however, the State Department said Tillerson still hoped to meet with NATO foreign ministers and had already proposed new dates for his meeting. “We are certainly appreciative of the effort to accommodate Secretary Tillerson,” State Department spokesman Mark Toner said, referring to the alliance’s attempt to reschedule the meeting at a more convenient time. “We have offered alternative dates that the secretary could attend,” Toner said, according to Reuters. Toner also reassured that “the United States remains 100 percent committed” to the alliance.