The U.S. military launched a series of strikes against Iranian targets early Wednesday after three merchant ships were struck in the waters off Oman, pushing the Strait of Hormuz back onto center stage as NATO opened the second day of its summit in Turkey.

U.S. Central Command said in a social media post that U.S. forces launched the strikes “to impose heavy costs for targeting and attacking commercial shipping crewed by innocent civilians in an international waterway.”

NATO leaders are trying to show increased military capabilities as the U.S. focus shifts from defending Europe. The alliance is holding a two-day summit in Ankara, Turkey, that will showcase military projects worth billions of dollars aimed at persuading Trump they are making a stronger Europe for a stronger NATO.

As the summit meetings began Wednesday, NATO Secretary-General Mark Rutte said the overnight U.S. strikes on Iran were necessary because Iran had violated the ceasefire.

U.S. President Donald Trump met with Turkish leader Recep Tayyip Erdoğan on Tuesday ahead of the summit and announced the U.S. will lift sanctions, opening the possibility of selling F-35 jets to Turkey over Israel’s objections.

Trump also criticized NATO’s abilities to function without U.S. leadership and power, expressing disappointment at the refusal of some NATO allies to join the Iran war he launched alongside Israel without consulting them.

Trump also insisted again that Greenland should be “controlled by the United States, not by Denmark.” Of all of his threats to NATO and its member countries, this has posed the greatest danger to the organization.

Here is the latest:

Danish prime minister vows to defend Greenland

Speaking at the NATO summit a day after U.S. President Donald Trump again expressed a desire for the U.S. to control Greenland, Denmark’s Prime Minister Mette Frederiksen said, “Greenland is of course not for sale.”

“We hope that all, including all allies, will respect the Greenland people right for self-determination,” she said. “And we are sovereign states and we need everybody to respect our territorial integrity and our sovereignty.”

She said Denmark is “ready to defend every inch of NATO including our own territory” in the event of an attack and would rely on NATO allies to honor their commitment to defend each other.

NATO chief supports US strikes on Iran

NATO Secretary-General Mark Rutte said Wednesday at the alliance’s summit in Ankara that the overnight U.S. strikes on Iran were necessary.

Iran had violated the ceasefire, Rutte said.

“I think it is totally crucial that the U.S. forcefully reacts,” Rutte said.

He expects NATO members to “reconfirm that Iran should never, ever get its hands on a nuclear capability” and also to reaffirm the importance of freedom of navigation in the Strait of Hormuz.