WASHINGTON/SEOUL, August 30 (Reuters) - President Donald Trump on Wednesday said "talking is not the answer" to the tense standoff with North Korea over its nuclear missile development, but his defense chief swiftly asserted that the United States still has diplomatic options. Trump's comment, coming a day after Pyongyang fired a ballistic missile over Japan that drew U.N. and other international condemnation, renewed his tough rhetoric toward reclusive, nuclear-armed and increasingly isolated North Korea. "The U.S. has been talking to North Korea, and paying them extortion money, for 25 years," Trump wrote on Twitter. "Talking is not the answer!" When asked by reporters just hours later if the United States was out of diplomatic solutions with North Korea amid rising tensions after a series of missile tests by Pyongyang, U.S. Defense Secretary Jim Mattis replied: "No." "We are never out of diplomatic solutions," Mattis said before a meeting with his South Korean counterpart at the Pentagon. "We continue to work together, and the minister and I share a responsibility to provide for the protection of our nations, our populations and our interests." Trump, who has vowed not to let North Korea develop nuclear missiles that can hit the mainland United States, had said in a statement on Tuesday that "all options are on the table." North Korea said the launch of an intermediate-range ballistic missile (IRBM) on Tuesday was to counter U.S. and South Korean military drills and was a first step in military action in the Pacific to "containing" the U.S. island territory of Guam. The 15-member U.N. Security Council condemned the firing of the missile over Japan as "outrageous," and demanded that North Korea halt its weapons program. The U.S.-drafted statement, which did not threaten new sanctions on North Korea, urged all nations to implement U.N. sanctions and said it was of "vital importance" that Pyongyang take immediate, concrete actions to reduce tensions. Trump's mention of payments to North Korea appeared to be a reference to previous U.S. aid to the country. A U.S. Congressional Research Service report said between 1995 and 2008, the United States provided North Korea with over $1.3 billion in assistance. Slightly more than 50 percent was for food and about 40 percent for energy assistance. The assistance was part of a nuclear deal that North Korea later violated. Since early 2009, the United States has provided virtually no aid to North Korea, though periodically there have been discussions about resuming large-scale food aid. The latest tweet by the Republican U.S. president drew criticism from some quarters in Washington. Democratic Senator Chris Murphy wrote on Twitter: "Bar is high, but this is perhaps the most dangerous, irresponsible tweet of his entire Presidency. Millions of lives at stake – not a game." North Korea's leader, Kim Jong Un, ordered the launch to be conducted for the first time from its capital, Pyongyang, and said more exercises with the Pacific as the target were needed, the North's KCNA news agency said on Wednesday. "The current ballistic rocket launching drill like a real war is the first step of the military operation of the KPA in the Pacific and a meaningful prelude to containing Guam," KCNA quoted Kim as saying. KPA stands for the Korean People's Army. Trump's secretaries of defense and state have emphasized finding a diplomatic solution to North Korea's nuclear ambitions. Earlier this month, Mattis told reporters the U.S. effort "is diplomatically led. It has diplomatic traction. It is gaining diplomatic results." Trump has offered divergent comments on North Korea in recent weeks. On Aug. 22, he tweeted that "I respect the fact that he is starting to respect us," referring to Kim, and that maybe "something positive can come about." On Aug. 8, Trump had threatened to unleash "fire and fury" against North Korea if it threatened the United States, and two days later delivered some more menacing words. North Korea threatened to fire four missiles into the sea near Guam, home to a major U.S. military presence, after Trump's "fire and fury" remark. 'KEY MILESTONE' The U.S. Defense Department's Missile Defense Agency and the crew of the USS John Paul Jones conducted a "complex missile defense flight test" off Hawaii early on Wednesday, resulting in the intercept of a medium-range ballistic missile target, the agency said. The agency's director, Lieutenant General Sam Greaves, called the test "a key milestone" in giving U.S. Navy Aegis Ballistic Missile Defense ships an enhanced capability, but did not mention North Korea. The United States and South Korea are technically still at war with North Korea because their 1950-53 conflict ended in a truce, not a peace treaty. North Korea routinely says it will never give up its weapons programs, saying they are necessary to counter perceived American hostility. In Geneva, American disarmament ambassador Robert Wood, addressing the U.N.-sponsored Conference on Disarmament, called for "concerted action" by the international community to pressure North Korea into abandoning its banned nuclear and missile program by fully enforcing economic sanctions. Washington has repeatedly urged China, North Korea's main ally and trading partner, to do more to rein in Pyongyang. Speaking during a visit to the Japanese city of Osaka, British Prime Minister Theresa May called on China to put more pressure on North Korea. Asked about her comments, Chinese Foreign Ministry spokeswoman Hua Chunying said some "relevant sides" were only selectively carrying out the U.N. resolutions by pushing hard on sanctions yet neglecting to push for a return to talks. She said this was not the attitude "responsible countries" should have when the "smell of gunpowder" remained strong over the Korean peninsula. "When it comes to sanctions, they storm to the front but when it comes to pushing for peace they hide at the very back," Hua told a daily news briefing. North Korea has conducted dozens of ballistic missile tests under Kim in defiance of U.N. sanctions, but firing a projectile over mainland Japan was a rare and provocative move. Tuesday's test was of the same Hwasong-12 missile Kim had threatened to use on Guam, but the test flight took it in another direction, over northern Japan's Hokkaido island and into the sea.