China and climate change loom large among Biden’s priorities.

China and global warming rank high on President Biden’s list of long-range global concerns. And as he travels to Europe on Wednesday for a week of summit meetings, U.S. allies wonder if they are being asked to sign up for a China containment policy, and whether Mr. Biden can deliver on climate?

While growing more repressive at home, China is expanding its commercial, military and political reach abroad — and its greenhouse gas emissions. The Europeans largely do not see China as the kind of rising threat that Washington does, but it is an argument where the United States is making headway.

Prime Minister Boris Johnson has signed on to an effort by Washington to ensure that Huawei, the Chinese telecommunications company, does not win new contracts to install 5G cellular networks in Britain. United States officials have raised concerns that Huawei equipment could become a back door to Chinese government surveillance or control of communications.

Some in Europe are following suit, but Mr. Biden’s aides said they felt blindsided when the European Union announced an investment agreement with China days before Mr. Biden’s inauguration. It reflected fears that if the continent got sucked into the U.S.-China rivalry, European companies would suffer.

Mr. Biden is going in the other direction: Last week he signed an executive order barring Americans from investing in Chinese companies that are linked to the country’s military or that sell technology used to repress dissent inside and outside China.

For the move to be effective, though, the allies would have to join. So far, few have expressed enthusiasm for the effort.

China, which now emits more climate-heating gases than the United States, Europe and Japan combined, is key to reaching ambitious goals to fight climate change. Peter Betts, the former lead climate negotiator for Britain and the European Union, said the test for Mr. Biden was whether he could lead other nations in a successful campaign to pressure Beijing.

Four years ago, President Donald J. Trump withdrew the United States from the 2016 Paris climate agreement.

Mr. Biden is reversing that stance, pledging to cut U.S. emissions 50 percent to 52 percent below 2005 levels by the end of the decade. He also wrote in an opinion essay in The Washington Post before the summit that with the United States back at the table, countries “have an opportunity to deliver ambitious progress.”

But world leaders remained leery of the United States’ willingness to enact serious emissions legislation and deliver on financial promises to poorer countries.