Mitt Romney on Tuesday used his maiden speech as a U.S. senator to call for closer ties between the United States and its European allies at a time when President Trump’s actions have called into question his commitment to transatlantic relations.

“It is in the United States’ most vital interest to see a strong NATO, a strong Europe, stronger ties with the free nations of Asia and the subcontinent, and with every free country,” the Utah Republican said. “We need to hold our friends closer, not neglect them or drive them away.”

Romney did not mention Trump by name in what was his first major address since joining the Senate in January, but his remarks amounted to a gentle rebuke of some of the president’s foreign policy priorities as Trump was in the midst of a trip to Europe.

While Trump has drawn criticism for seeking a warmer relationship with Russia, Romney condemned the nation in no uncertain terms.

“Russia continues its malign effort, of course, violating treaties, invading sovereign nations, pursuing nuclear superiority, interfering in elections, spreading lies and hate, protecting the world’s worst actors from justice and promoting authoritarianism,” Romney said.

But he said Russia is a country on the decline and no longer “our number one geopolitical adversary,” arguing that China now holds that distinction.

“When it was admitted to the World Trade Organization, the expectation was that China would embrace the rules of the global order, including, eventually, respect for human rights,” Romney said. “It’s done the opposite, imprisoning millions in re-education camps; brutally repressing dissent; censoring the media and Internet; seizing land and sea that don’t belong to it; and flouting the global rules of free and fair competition.”

While the Trump administration and Congress widely understand China’s aggression, Romney said, the U.S. response to date has been “ad hoc, short-term or piecemeal.”

“It is past time for us to construct a comprehensive strategy to meet the challenge of an ambitious and increasingly hostile China,” he said.

Romney argued that one advantage the United States has over China is its alliances.

“America has many friends, China has very few,” he said.

During Trump’s time as president, relationships with U.S. allies have been strained by questions about his commitment to NATO and his decisions to withdraw the United States from several international accords, including the Paris climate agreement.

Romney, who declined to vote for Trump in 2016, instead writing in his wife’s name, has shared some of Trump’s policy priorities since arriving in the Senate but not hesitated to speak out when they have differences.