TOKYO (AP) — Japan' s Defense Minister Gen Nakatani was welcomed aboard a South Korean warship during its port call near Tokyo on Wednesday, a first for a Japanese defense chief, as the two countries step up security ties against a backdrop of growing tension in the region.

Nakatani greeted and spoke with South Korean sailors aboard their Dokdo-class amphibious assault ship ROKS Marado which was making a port call at a Japanese Maritime Self-Defense Force base in Yokosuka, west of Tokyo, on Thursday.

“Japan-South Korea security and defense cooperation have become more important than ever as we face an extremely severe security environment and global issues,” Nakatani told a welcome ceremony. He was speaking two days after North Korea fired a barrage of short-range missiles into the sea just east of the Korean Peninsula shortly before the U.S. presidential election.

Nakatani said Japan will further deepen defense ties with South Korea and relations with the United States.

Last week, North Korean leader Kim Jong Un supervised a test flight of the country’s newest intercontinental ballistic missile designed to reach the U.S. mainland.

The crewmembers of the South Korean fleet of three warships were expected to take part in a joint training program with their Japanese counterparts while in Yokosuka.

Since early last year, under pressure from Washington and with tension growing in the region, the leaders of the two Asian neighbors worked to repair ties badly frayed over grievances stemming from Japan’s atrocities during its 1910-45 occupation of the Korean Peninsula. The two countries have since revived high-level talks and cooperation from in areas including the economy and defense.

Nakatani's appearance on the South Korean warship underscores the improvement in relations since last year. The leaders of Japan, South Korea and the United States have also agreed to bolster their trilateral security ties and formalize their annual summit.