Japan said Saturday that Australia and Canada will join the multilateral effort to monitor North Korean attempts to evade U.N. Security Council sanctions through maritime smuggling.

The Foreign Ministry said the two countries will deploy patrol aircraft to U.S. Kadena Air Base in Okinawa Prefecture. They are expected to engage in monitoring and surveillance activities to prevent ship-to-ship transfers of goods at sea by North Korea in waters around the Japanese archipelago, the Korean Peninsula and in the East China Sea.

“Japan welcomes these activities from the viewpoint of upholding maximum pressure on North Korea,” the ministry said in a statement.

The expansion of the surveillance effort, which already involves the United States and Japan, comes as North Korean leader Kim Jong Un and South Korean President Moon Jae-in held the first inter-Korean summit in over a decade on Friday, agreeing to pursue “complete” denuclearization of the Korean Peninsula.

The British Royal Navy has already announced it will deploy the frigate Sutherland to waters around Japan to monitor maritime smuggling. Britain’s navy also held a two-day joint military exercise with the Maritime Self-Defense Force that began on Friday.

Security experts believe North Korea has been engaging in illicit activities at sea to procure much-needed supplies of fuel and other goods squeezed by U.N.-led sanctions.

Japan has noted and reported to the United Nations multiple cases of suspected ship-to-ship transfers involving North Korean and foreign-registered tankers in the East China Sea since January.