U.S. Defense Secretary Jim Mattis has told Washington's NATO allies that the United States will "moderate its commitment" to the alliance unless they boost their defense spending.
Mattis told NATO defense ministers gathered at NATO headquarters in Brussels on February 15 that U.S. taxpayers could no longer carry "a disproportionate share of the defense of Western values."
Mattis told the ministers that if their countries "do not want to see America moderate its commitment to this alliance," each of their capitals "need to show support for our common defense."
Earlier on February 15, Mattis said the NATO alliance "remains a fundamental bedrock for the United States and for all the transatlantic community."
"As President Trump has stated, he had strong support for NATO," Mattis told reporters in Brussels ahead of his meeting with NATO defense ministers -- his first since being sworn in on January 27 as the defense chief in President Donald Trump's cabinet.
NATO members have voiced concern about Trump's attitude toward the alliance, which he referred to as "obsolete" during the 2016 U.S. presidential election campaign.
NATO allies have also expressed concerns about Trump's campaign statements suggesting he may take a softer approach toward Russia than his predecessor.
Trump has also criticized NATO members that fail to meet the alliance's defense spending target of 2 percent of their gross domestic product (GDP).
Mattis told reporters on February 15 that it was "a fair demand that all who benefit from the best defense in the world carry their proportionate share of the necessary cost to defend freedom."
German Defense Minister Ursula von der Leyen supported the U.S. position of February 15, telling reporters ahead of the NATO ministers meeting that it was a "question of fairness that we Europeans together also make an effort and the burden [of defense spending] is not too much on the Americans."
In 2014, the year Russia seized Crimea and backed separatists in a war that has since killed more than 9,750 people in eastern Ukraine, NATO leaders committed to halt defense spending cuts and move to raise their military budgets to 2 percent of GDP within a decade.
Twenty-four of the 28 members have stopped cutting defense spending. Stoltenberg has said the United States, Britain, Poland, Greece, and Estonia are "already meeting the 2 percent target," while Latvia, Lithuania, and Romania are getting close.
The ministers said they will also aim to send a clear signal of unity.
"I'm absolutely certain that the message of this meeting will be a message of transatlantic unity, of the importance of that we stand together and protect each other, and a very strong commitment of the United States to NATO," NATO Secretary-General Jens Stoltenberg told journalists before the meeting.
The fight against terrorism, in particular against the extremist group Islamic State (IS), was also expected to be high on the agenda during the two-day meeting.
The ministers were set to decide to establish a coordination center in Naples, Italy, where intelligence from countries such as Libya, Syria, or Iraq would be analyzed.
"This will help us to coordinate information on crises...and help us address terrorism and other challenges stemming from the region," Stoltenberg said.