Trump’s low regard for NATO’s core principles makes it unlikely that the alliance will survive without the U.S

Since returning to office, U.S. President Donald Trump has questioned NATO 's collective defense commitment.

Julian Zelizer : Given Trump ’s low regard for NATO , it would be no surprise if his administration decided to withdraw from the alliance.

He says NATO 's Article 5 collective-defense provision says an attack on any alliance member will be considered an attack.

Zelizer says the U.K. has been NATO 's leading member and principal security provider for 76 years .

Frida Ghitis: NATO has worked only because the U.S. has played a dominant and unifying role.

She says the United States has always occupied key positions of NATO ’s command structure.

Ghitis says U.N. nuclear weapons, including those that are deployed in Europe and shared with allied forces, constitute NATO 's ultimate deterrent.

The 2009 Treaty of Lisbon further enshrined a mutual defense commitment.

NATO 's new regional defense plans, drawn up since Russia ’s full-scale invasion of Ukraine , provide the framework for doing so.

Europeanization of NATO will require three things that are currently in short supply: money, time, and U.S. cooperation.