TOKYO — A British warship has arrived in Japan to join international efforts to enforce sanctions on North Korea by monitoring any prohibited trading by the country at sea.

The frigate HMS Southerland, which entered Yokosuka — home to the U.S. Navy's 7th Fleet — on Wednesday, will join exercises with Japan's navy and monitor attempts by North Korea to evade U.N.-imposed sanctions, said Royal Navy Capt. Paul Casson.

The ship is the first of three British warships planned for deployment in the region this year to participate in the monitoring and join exercises with Japan and other countries in the Asia-Pacific region, he said.

Britain says its warships' presence demonstrates its commitment to the region's peace and stability.

The U.N. has toughened its sanctions on North Korea over its nuclear weapons development, including banning ship-to-ship transfers of oil and other goods to North Korea. Recent U.N. and U.S. watch lists and Japanese surveillance reports have identified ships and companies suspected of helping North Korea evade the sanctions.

Despite North Korea's recent diplomatic outreach to South Korea, the U.S. and China, the U.S. and its allies say pressure should be maintained until it takes concrete actions to abandon its nuclear weapons.

Japan is also stepping up its missile defense and other capabilities in response to North Korea's nuclear and missile tests last year.

During its deployment in the region, the British frigate will be joined by the amphibious assault ship HMS Albion to help enforce the U.N. sanctions. A third ship, the HMS Argyll, is to be deployed later in the year.

"So I would say in 2018 I think the Royal Navy and British military are going to do part of the pressure campaign and provide a highly visible message to the regime of North Korea," Casson said.