North Korean leader Kim Jong Un called for a rapid buildup of naval combat power to counter "hostile acts of the enemies," as Pyongyang warned the United States that it will mount a stronger response to Washington's "hostile policy" toward the country, state media reported on Wednesday. Kim made the remarks during a visit to the Nampho shipyard Monday, where he was briefed on the shipyard's ongoing upgrades and inspected a new warship under construction, state-run Korean Central News Agency reported. "It is vital and important requirement of the times to rapidly bolster up the surface and underwater combat power for defending the national sovereignty in the sea under various threats," Kim said. Read: North Korea tests tactical ballistic missile cluster warhead The recent geopolitical environment and hostile acts of the enemies in the region prove the need for "the most developed and powerful warship," he added. Without providing the ship's specifications, North Korean media said the vessel is "designed to carry out its complex operational mission in consideration of the present-day warfare." 'Dialogue with US remains an 'option' Kim's powerful sister Kim Yo-jong Wednesday said that dialogue with Washington remains "an option for peace, but that it would not be necessary for its own interest." She said that the continued "hostile signal" by Washington was compelling the regime to reconsider the "true nature" of the US. "The choice for peace includes dialogue of course, but this is not surely equated with national interests for us," Kim said in a statement. Her remarks came a day after she rejected the FBI findings that Pyongyang was behind the theft of more than $6 billion in cryptocurrency from Binance, the world's largest cryptocurrency exchange. Read More: North Korea fires dozen ballistic missiles toward East Sea: South Korea "The so-called 'cryptocurrency hacking case by the DPRK' is no more than a tip of iceberg that shows the essence of the US hostile policy toward the DPRK," she maintained. DPRK refers to North Korea's official name, the Democratic People's Republic of Korea. "The US abandonment of its hostile policy" toward Pyongyang "is a major premise and key to solving all problems," she said, adding that North Korea has no reason to engage in talks with the US unless that happens. She warned that Pyongyang would respond to what it views as continued US hostility.