UNITED NATIONS — The United Nations Security Council placed new sanctions on North Korea on Friday that significantly choke off fuel supplies and order North Koreans working overseas to return home, in what may prove the last test of whether any amount of economic pressure can force the isolated country to reverse course on its nuclear weapons program.

The sanctions, proposed by the United States and adopted by a vote of 15 to 0, were the third imposed this year, in an escalating effort to force the North into negotiations. China and Russia joined in the vote, in a striking display of unity, but only after the Trump administration agreed to soften a couple of the provisions.

Under the new sanctions, the amount of refined petroleum North Korea can import each year will be cut by 89 percent, exacerbating fuel shortages. Roughly 100,000 North Korean laborers who work in other countries, a critical source of hard currency, will be expelled within two years. Nations will be urged to inspect all North Korean shipping and halt ship-to-ship transfers of fuel, which the North has used to evade sanctions.

But the resolution does not permit countries to hail or board North Korean ships in international waters, which the Trump administration proposed in September. That would be the most draconian measure, because it would enable the United States Navy and its Pacific allies to create a cordon around the country, though Pentagon officials say it would risk setting off a firefight between North Korea and foreign navies.