The first jets in an air wing of advanced U.S. stealth F-22 fighters that is temporarily being deployed to Japan arrived Wednesday at Kadena Air Base in Okinawa Prefecture, according to Japanese government sources.

The four jets, which arrived at the base at around 3:10 p.m., will be joined by 10 others to eventually comprise a fleet of 14 F-22s. The aircraft are expected to be stationed at the base for about a month, the sources said.

The deployment comes as preparations proceed for the June 12 summit in Singapore between U.S. President Donald Trump and North Korea leader Kim Jong Un, which is drawing attention to the movements made by U.S. forces in Japan.

Earlier in the week, the nuclear-powered aircraft carrier USS Ronald Reagan left its home base in Yokosuka, near Tokyo, for an extended patrol in the region.

And in Hawaii, Japanese and U.S. defense chiefs on Tuesday affirmed their countries would maintain pressure and sanctions on North Korea until it abandoned its nuclear weapons and ballistic missile program.